Barrier film

ABSTRACT

A barrier film is disclosed that includes a polymeric film substrate and at least first and second polymer layers separated by an inorganic barrier layer. The first polymer layer is disposed on the polymeric film substrate. At least one of the first or second polymer layers is prepared from co-deposited amino silane and acrylate or methacrylate monomer. A method of making the barrier film is also disclosed.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/175,495, filed Jul. 1, 2011, which claims priority from U.S.Provisional Application Ser. No. 61/361,133, filed Jul. 2, 2010, thedisclosures of which are incorporated by reference in their entiretyherein.

BACKGROUND

Emerging solar technologies such as organic photovoltaic devices (OPVs)and thin film solar cells like copper indium gallium di-selenide (CIGS)require protection from water vapor and need to be durable (e.g., toultra-violet (UV) light) in outdoor environments. Typically, glass hasbeen used as an encapsulating material for such solar devices becauseglass is a very good barrier to water vapor, is optically transparent,and is stable to UV light. However, glass is heavy, brittle, difficultto make flexible, and difficult to handle. There is interest indeveloping transparent flexible encapsulating materials to replace glassthat will not share the drawbacks of glass but have glass-like barrierproperties and UV stability, and a number of flexible barrier films havebeen developed that approach the barrier properties of glass.

SUMMARY

Despite progress in encapsulant technology, the barrier and durabilityrequirements in solar applications continue to be a challenge, andfurther work is needed to bring effective, flexible encapsulatingsolutions to the solar market. The present disclosure providesassemblies useful, for example, for encapsulating solar devices. Theassemblies disclosed herein are generally flexible, transmissive tovisible and infrared light, and have excellent barrier properties.

While fluoropolymer and other weatherable films have been said to beuseful components of encapsulating systems for flexible photovoltaiccells (e.g., in U.S. Pat. App. Pub. No. 2003/0029493), fluoropolymerfilms may have coefficients of thermal expansion in excess of 100 partsper million per Kelvin (ppm/K), while flexible carriers (e.g., polyimidefilms or metal foils) useful for photovoltaic cells may havecoefficients of thermal expansion of less than 30 ppm/K. Such acoefficient of thermal expansion mismatch between a fluoropolymer filmand a flexible carrier can bring about thermal stresses in anencapsulated flexible photovoltaic cell. It has now been discovered thatunder certain thermal lamination conditions (e.g., 150° C.),encapsulating systems including multilayer barrier films onfluoropolymers laminated to low CTE flexible substrates with thermallycuring encapsulants (e.g., ethylene-vinyl acetate) develop thermalstresses that can cause delamination.

Flexible photovoltaic cells (e.g., CIGS) have relatively high profiles(e.g., higher profiles than, for example, organic electroluminescencedevices). Thin-film CIGS cells typically have bussing and tabbingribbons that may, for example, stand more than 0.15 mm above the surfaceof the cell. These high profile components can act as stressconcentrators that may exacerbate the problems caused by CTE mismatch.

The barrier assemblies according to the present disclosure are useful,for example, for minimizing the affects of CTE mismatch between aweatherable top layer and a flexible photovoltaic module that can resultafter a high temperature lamination.

In one aspect, the present disclosure provides an assembly that includesa barrier film interposed between a first polymeric film substrate and afirst major surface of a pressure sensitive adhesive layer. The firstpolymeric film substrate has a first coefficient of thermal expansion.The pressure sensitive adhesive layer has a second major surfaceopposite the first major surface that is disposed on a second polymericfilm substrate having a second coefficient of thermal expansion. Thesecond coefficient of thermal expansion is at least 40 parts per millionper Kelvin higher than the first coefficient of thermal expansion. Theassembly is transmissive to visible and infrared light.

In another aspect, the present disclosure provides an assembly thatincludes a barrier film interposed between a first polymeric filmsubstrate and a first major surface of a pressure sensitive adhesivelayer. The first polymeric film substrate has a coefficient of thermalexpansion up to 50 parts per million per Kelvin. The pressure sensitiveadhesive layer has a second major surface opposite the first majorsurface that is disposed on a second polymeric film substrate that isresistant to degradation by ultraviolet light. The assembly istransmissive to visible and infrared light.

In this application, terms such as “a”, “an” and “the” are not intendedto refer to only a singular entity, but include the general class ofwhich a specific example may be used for illustration. The terms “a”,“an”, and “the” are used interchangeably with the term “at least one”.The phrases “at least one of” and “comprises at least one of” followedby a list refers to any one of the items in the list and any combinationof two or more items in the list. All numerical ranges are inclusive oftheir endpoints and non-integral values between the endpoints unlessotherwise stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of thefollowing detailed description of various embodiments of the disclosurein connection with the accompanying drawings, in which:

FIG. 1 illustrates an assembly according to some embodiments of thepresent disclosure using a schematic side view;

FIG. 2 illustrates a schematic side view of an embodiment of an assemblyaccording to the present disclosure in which the barrier film haslayers;

FIG. 3 illustrates a schematic side view of another embodiment of anassembly according to the present disclosure in which the assemblyincludes a photovoltaic module; and

FIG. 4 illustrates a schematic side view of an embodiment of an assemblyaccording to the present disclosure in which the barrier film has layersand in which the assembly includes a photovoltaic module;

DETAILED DESCRIPTION

Barrier assemblies according to the present disclosure are transmissiveto visible and infrared light. The term “transmissive to visible andinfrared light” as used herein can mean having an average transmissionover the visible and infrared portion of the spectrum of at least about75% (in some embodiments at least about 80, 85, 90, 92, 95, 97, or 98%)measured along the normal axis. In some embodiments, the visible andinfrared light-transmissive assembly has an average transmission over arange of 400 nm to 1400 nm of at least about 75% (in some embodiments atleast about 80, 85, 90, 92, 95, 97, or 98%). Visible and infraredlight-transmissive assemblies are those that do not interfere withabsorption of visible and infrared light, for example, by photovoltaiccells. In some embodiments, the visible and infrared light-transmissiveassembly has an average transmission over a range of wavelengths oflight that are useful to a photovoltaic cell of at least about 75% (insome embodiments at least about 80, 85, 90, 92, 95, 97, or 98%). Thefirst and second polymeric film substrates, pressure sensitive adhesivelayer, and barrier film can be selected based on refractive index andthickness to enhance transmission to visible and infrared light.

Barrier assemblies according to the present disclosure are typicallyflexible. The term “flexible” as used herein refers to being capable ofbeing formed into a roll. In some embodiments, the term “flexible”refers to being capable of being bent around a roll core with a radiusof curvature of up to 7.6 centimeters (cm) (3 inches), in someembodiments up to 6.4 cm (2.5 inches), 5 cm (2 inches), 3.8 cm (1.5inch), or 2.5 cm (1 inch). In some embodiments, the flexible assemblycan be bent around a radius of curvature of at least 0.635 cm (¼ inch),1.3 cm (½ inch) or 1.9 cm (¾ inch).

Barrier assemblies according to the present disclosure generally do notexhibit delamination or curl that can arise from thermal stresses orshrinkage in a multilayer structure. Herein, curl is measured using acurl gauge described in “Measurement of Web Curl” by Ronald P. Swansonpresented in the 2006 AWEB conference proceedings (Association ofIndustrial Metallizers, Coaters and Laminators, Applied Web HandlingConference Proceedings, 2006). According to this method, curl can bemeasured to the resolution of 0.25 m⁻¹ curvature. In some embodiments,barrier assemblies according to the present disclosure exhibit curls ofup to 7, 6, 5, 4, or 3 m⁻¹. From solid mechanics, the curvature of abeam is known to be proportional to the bending moment applied to it.The magnitude of bending stress in turn is known to be proportional tothe bending moment. From these relations the curl of a sample can beused to compare the residual stress in relative terms. Barrierassemblies also typically exhibit high peel adhesion to EVA, and othercommon encapsulants for photovoltaics, cured on a substrate. Theproperties of the barrier assemblies disclosed herein typically aremaintained even after high temperature and humidity aging.

Embodiments of assemblies according to the present disclosure areillustrated in FIGS. 1 to 4. FIG. 1 illustrates an assembly according tosome embodiments of the present disclosure. Assembly 100 includes abarrier film 120, which can be described as having two major surfaces.On the lower major surface in the illustrated embodiment, the barrierfilm 120 is in contact with a first polymeric film substrate 140. On theupper major surface in the illustrated embodiment, the barrier film 120is in contact with a pressure sensitive adhesive layer 110, whichadheres the barrier film 120 to a major surface of the second polymericfilm substrate 130.

FIG. 2 illustrates another assembly 200 according to some embodiments ofthe present disclosure, in which the barrier film has layers 228, 226,and 224. In the illustrated embodiment, first and second polymer layers224 and 228 are separated by a visible light-transmissive inorganicbarrier layer 226, which is in intimate contact with the first andsecond polymer layers 224 and 228. In the illustrated embodiment, thefirst polymer layer 224 is in contact with the first polymeric filmsubstrate 240, and the second polymer layer 228 is in contact withpressure sensitive adhesive layer 210, which adheres the second polymerlayer 228 to a major surface of the second polymeric film substrate 230.The second polymer layer 228 and inorganic barrier layer 226 can becalled a dyad. Although only one dyad is shown in FIG. 2 (and FIG. 4),assembly 200 can include additional dyads (e.g., 1, 2, 3, 5, 10, or moreadditional dyads) between pressure sensitive adhesive layer 210 andfirst polymer layer 224. Furthermore, in some embodiments, an additionalinorganic barrier layer (not shown), or half dyad, may be between thesecond polymer layer 228 and the pressure sensitive adhesive layer 210.

In FIG. 3, assembly 300 is similar to assembly 100 illustrated in FIG. 1and includes second polymeric film substrate 330 adhered to the uppersurface of barrier film 320 with pressure sensitive adhesive layer 310and first polymeric film substrate 340 in contact with the lower majorsurface of the barrier film 320. In FIG. 4, the barrier film in assembly400 has layers 428, 426, and 424 and is similar to assembly 200illustrated in FIG. 2. In the embodiments illustrated in FIGS. 3 and 4,assemblies 300 and 400 include a photovoltaic cell 360 and 460 (e.g., aCIGS cell). The upper surface of the photovoltaic cell 360 and 460 is incontact with an encapsulant 350 and 450 joining the photovoltaic cell360 and 460 to the barrier assembly 100 and 200, respectively. The lowersurface of the photovoltaic cell 360 and 460 is in contact with anencapsulant 350 and 450 joining the photovoltaic cell 360 and 460 tobacking film 370 and 470, respectively.

First polymeric film substrates 140, 240, 340, and 440; second polymericfilm substrates 130, 230, 330, and 430; barrier films 120 and 320; andpressure sensitive adhesive 110, 210, 310, and 410 useful for practicingthe present disclosure are described in more detail below. In someembodiments of the assemblies disclosed herein, a pressure sensitiveadhesive disclosed herein is disposed on a barrier assembly. In theseembodiments, the barrier assembly is part of the assembly and comprisesthe polymeric film substrates and the barrier film described below.Accordingly, the description that follows refers to polymeric filmsubstrates and barrier films that may be in an assembly according to thepresent disclosure, a barrier assembly useful for practicing the presentdisclosure, or both.

First Polymeric Film Substrate

Assemblies according to the present disclosure comprise a firstpolymeric film substrate 140, 240, 340, 440. In the context of polymericfilms (e.g., first and second polymeric film substrates), the term“polymeric” will be understood to include organic homopolymers andcopolymers, as well as polymers or copolymers that may be formed in amiscible blend, for example, by co-extrusion or by reaction, includingtransesterification. The terms “polymer” and “copolymer” include bothrandom and block copolymers.

The first polymeric film substrate may be selected, for example, so thatits CTE is about the same (e.g., within about 10 ppm/K) or lower thanthe CTE of the device (e.g., flexible photovoltaic device) to beencapsulated. In other words, the first polymeric substrate may beselected to minimize the CTE mismatch between the first polymericsubstrate and the device to be encapsulated. In some embodiments, thefirst polymeric film substrate has a CTE that is within 20, 15, 10, or 5ppm/K of the device to be encapsulated. In some embodiments, it may bedesirable to select the first polymeric film substrate that has a lowCTE. For example, in some embodiments, the first polymeric filmsubstrate has a CTE of up to 50 (in some embodiments, up to 45, 40, 35,or 30) ppm/K. In some embodiments, the CTE of the first polymeric filmsubstrate is in a range from 0.1 to 50, 0.1 to 45, 0.1 to 40, 0.1 to 35,or 0.1 to 30 ppm/K. When the first polymeric film substrate is selected,the difference between the CTE of the first polymeric film substrate andthe second polymeric film substrate (described below) may be, in someembodiments, at least 40, 50, 60, 70, 80, 90, 100, or 110 ppm/K. Thedifference between the CTE of the first polymeric film substrate and thesecond polymeric film substrate may be, in some embodiments, up to 150,140, or 130 ppm/K. For example, the range of the CTE mismatch betweenthe first and second polymeric film substrates may be, for example, 40to 150 ppm/K, 50 to 140 ppm/K, or 80 to 130 ppm/K. The CTE of substratescan be determined by thermal mechanical analysis. And the CTE of manysubstrates can be found in product data sheets or handbooks.

In some embodiments, the first polymeric film substrate has a modulus(tensile modulus) up to 5×10⁹ Pa. The tensile modulus can be measured,for example, by a tensile testing instrument such as a testing systemavailable from Instron, Norwood, Mass., under the trade designation“INSTRON 5900”. In some embodiments, the tensile modulus of the firstpolymeric film substrate is up to 4.5×10⁹ Pa, 4×10⁹ Pa, 3.5×10⁹ Pa, or3×10⁹ Pa. The first and second polymeric film substrates may beselected, for example, such that the first polymeric film substrate hasa higher tensile modulus than the second polymeric film substrate. Thisselection may maximize dimensional stability, for example, when there isa CTE mismatch of at least 40 ppm/K between the first and secondpolymeric film substrates. In some embodiments, the ratio of the tensilemodulus of the first polymeric film substrate to the tensile modulus ofthe second polymeric film substrate is at least 2 to 1 (in someembodiments, at least 3 to 1 or 4 to 1). Typically, the tensile modulusof PET is about 4×10⁹ Pa, and the tensile modulus of ETFE is about 1×10⁹Pa.

The first polymeric film substrate is typically a support onto which abarrier film can be deposited (e.g., using the methods describedhereinbelow). In some embodiments, the first polymeric film substrate isheat-stabilized (e.g., using heat setting, annealing under tension, orother techniques) to minimize shrinkage up to at least the heatstabilization temperature when the support is not constrained. Exemplarysuitable materials for the first polymeric film substrate includepolyethylene terephthalate (PET), polyethylene naphthalate (PEN),polyetheretherketone (PEEK), polyaryletherketone (PAEK), polyarylate(PAR), polyetherimide (PEI), polyarylsulfone (PAS), polyethersulfone(PES), polyamideimide (PAI), and polyimide, any of which may optionallybe heat-stabilized. These materials are reported to have CTEs of in arange from <1 to about 42 ppm/K. Suitable first polymeric filmsubstrates are commercially available from a variety of sources.Polyimides are available, for example, from E.I. Dupont de Nemours &Co., Wilmington, Del., under the trade designation “KAPTON” (e.g,“KAPTON E” or “KAPTON H”); from Kanegafugi Chemical Industry Companyunder the trade designation “APICAL AV”; from UBE Industries, Ltd.,under the trade designation “UPILEX”. Polyethersulfones are available,for example, from Sumitomo. Polyetherimides are available, for example,from General Electric Company, under the trade designation “ULTEM”.Polyesters such as PET are available, for example, from DuPont TeijinFilms, Hopewell, Va.

For any of the embodiments of the first polymeric film substratedescribed above, the major surface of the first polymeric film substrateonto which the barrier film disclosed herein is deposited or otherwisejoined can be treated to improve adhesion to the barrier film. Usefulsurface treatments include electrical discharge in the presence of asuitable reactive or non-reactive atmosphere (e.g., plasma, glowdischarge, corona discharge, dielectric barrier discharge or atmosphericpressure discharge); chemical pretreatment; or flame pretreatment. Aseparate adhesion promotion layer may also be formed between the majorsurface of the first polymeric film substrate and the barrier film. Theadhesion promotion layer can be, for example, a separate polymeric layeror a metal-containing layer such as a layer of metal, metal oxide, metalnitride or metal oxynitride. The adhesion promotion layer may have athickness of a few nanometers (nm) (e.g., 1 or 2 nm) to about 50 nm ormore. In some embodiments, one side (that is, one major surface) of thefirst polymeric film substrate can be treated to enhance adhesion to thebarrier film, and the other side (that is, major surface) can be treatedto enhance adhesion to a device to be covered or an encapsulant (e.g.,EVA) that covers such a device. Some useful first polymeric filmsubstrates that are surface treated (e.g., with solvent or otherpretreatments) are commercially available, for example, from Du PontTeijin Films. For some of these films, both sides are surface treated(e.g., with the same or different pretreatments), and for others, onlyone side is surface treated.

In some embodiments, the first polymeric film substrate has a thicknessfrom about 0.05 mm to about 1 mm, in some embodiments, from about 0.1 mmto about 0.5 mm or from 0.1 mm to 0.25 mm. Thicknesses outside theseranges may also be useful, depending on the application. In someembodiments, the first polymeric film substrate has a thickness of atleast 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, or 0.13 mm. Inembodiments wherein the CTE of the second polymeric film substrate ismore than 40 ppm/K higher than the CTE of the first polymeric filmsubstrate, the ratio of the thickness of the first polymeric filmsubstrate to the second polymeric film substrate may be adjusted and theto minimize the affect of CTE mismatch. For example, the ratio of thethicknesses of the first polymeric film substrate to the secondpolymeric film substrate may be in a range from 5:2 to 10:2 (in someembodiments, in a range from 5:2 to 8:2 or 5:2 to 7:2). In someembodiments, the ratio of the thicknesses of the first polymeric filmsubstrate to the second polymeric film substrate is at least 5:2, 6:2,7:2, or 8:2. As shown in the Examples, below, reducing the thickness ofthe second polymeric film substrate (e.g., the ETFE layer in theexamples), which has a higher CTE and lower stiffness than the firstpolymeric film substrate, relative to the first polymeric film substratereduced the bending moment in the assembly. Similarly, reducing thethickness of the first polymeric film layer (e.g., the PET layer in theExamples) increased the stress in the assembly.

Second Polymeric Film Substrate

Assemblies according to the present disclosure comprise a secondpolymeric film substrate 130, 230, 330, 430. The second polymeric filmsubstrate is generally flexible and transmissive to visible and infraredlight and comprises organic film-forming polymers. Useful materials thatcan form second polymeric film substrates include polyesters,polycarbonates, polyethers, polyimides, polyolefins, fluoropolymers, andcombinations thereof.

In embodiments wherein the assembly according to the present disclosureis used, for example, for encapsulating solar devices, it is typicallydesirable for the second polymeric film substrate to be resistant todegradation by ultraviolet (UV) light and weatherable. Photo-oxidativedegradation caused by UV light (e.g., in a range from 280 to 400 nm) mayresult in color change and deterioration of optical and mechanicalproperties of polymeric films. The second polymeric film substratesdescribed herein can provide, for example, a durable, weatherabletopcoat for a photovoltaic device. The substrates are generally abrasionand impact resistant and can prevent degradation of, for example,photovoltaic devices when they are exposed to outdoor elements.

A variety of stabilizers may be added to the polymeric film substrate toimprove its resistance to UV light. Examples of such stabilizers includeat least one of ultra violet absorbers (UVA) (e.g., red shifted UVabsorbers), hindered amine light stabilizers (HALS), or anti-oxidants.These additives are described in further detail below. In someembodiments, the phrase “resistant to degradation by ultraviolet light”means that the second polymeric film substrate includes at least oneultraviolet absorber or hindered amine light stabilizer. In someembodiments, the phrase “resistant to degradation by ultraviolet light”means that the second polymeric film substrate at least one of reflectsor absorbs at least 50 percent of incident ultraviolet light over atleast a 30 nanometer range in a wavelength range from at least 300nanometers to 400 nanometers. In some of these embodiments, the secondpolymeric film substrate need not include UVA or HALS.

The UV resistance of the second polymeric film substrate can beevaluated, for example, using accelerated weathering studies.Accelerated weathering studies are generally performed on films usingtechniques similar to those described in ASTM G-155, “Standard practicefor exposing non-metallic materials in accelerated test devices that uselaboratory light sources”. The noted ASTM technique is considered asound predictor of outdoor durability, that is, ranking materialsperformance correctly. One mechanism for detecting the change inphysical characteristics is the use of the weathering cycle described inASTM G155 and a D65 light source operated in the reflected mode. Underthe noted test, and when the UV protective layer is applied to thearticle, the article should withstand an exposure of at least 18,700kJ/m² at 340 nm before the b* value obtained using the CIE L*a*b* spaceincreases by 5 or less, 4 or less, 3 or less, or 2 or less before theonset of significant cracking, peeling, delamination or haze.

In some embodiments, the second polymeric film substrate disclosedherein comprises a fluoropolymer. Fluoropolymers typically are resistantto UV degradation even in the absence of stabilizers such as UVA, HALS,and anti-oxidants. Useful fluoropolymers includeethylene-tetrafluoroethylene copolymers (ETFE),tetrafluoroethylene-hexafluoropropylene copolymers (FEP),tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymers(THV), polyvinylidene fluoride (PVDF), blends thereof, and blends ofthese and other fluoropolymers.

As described above, the CTE of fluoropolymer films is typically highrelative to films made from hydrocarbon polymers. For example, the CTEof a fluoropolymer film may be at least 75, 80, 90, 100, 110, 120, or130 ppm/K. For example, the CTE of ETFE may be in a range from 90 to 140ppm/K.

The substrates comprising fluoropolymer can also include non-fluorinatedmaterials. For example, a blend of polyvinylidene fluoride andpolymethyl methacrylate can be used. Useful flexible, visible andinfrared light-transmissive substrates also include multilayer filmsubstrates. Multilayer film substrates may have different fluoropolymersin different layers or may include at least one layer of fluoropolymerand at least one layer of a non-fluorinated polymer. Multilayer filmscan comprise a few layers (e.g., at least 2 or 3 layers) or can compriseat least 100 layers (e.g., in a range from 100 to 2000 total layers ormore). The different polymers in the different multilayer filmsubstrates can be selected, for example, to reflect a significantportion (e.g., at least 30, 40, or 50%) of UV light in a wavelengthrange from 300 to 400 nm as described, for example, in U.S. Pat. No.5,540,978 (Schrenk). Such blends and multilayer film substrates may beuseful for providing UV resistant substrates that have lower CTEs thanthe fluoropolymers described above.

Useful second polymeric film substrates comprising a fluoropolymer canbe commercially obtained, for example, from E.I. duPont De Nemours andCo., Wilmington, Del., under the trade designation “TEFZEL ETFE” and“TEDLAR”, from Dyneon LLC, Oakdale, Minn., under the trade designations“DYNEON ETFE”, “DYNEON THV”, “DYNEON FEP”, and “DYNEON PVDF”, from St.Gobain Performance Plastics, Wayne, N.J., under the trade designation“NORTON ETFE”, from Asahi Glass under the trade designation “CYTOPS”,and from Denka Kagaku Kogyo KK, Tokyo, Japan under the trade designation“DENKA DX FILM”.

Some useful second polymeric film substrates other than fluoropolymersare reported to be resistant to degradation by UV light in the absenceof UVA, HALS, and anti-oxidants. For example, certain resorcinolisophthalate/terephthalate copolyarylates, for example, those describedin U.S. Pat. Nos. 3,444,129; 3,460,961; 3,492,261; and 3,503,779 arereported to be weatherable. Certain weatherable multilayer articlescontaining layers comprising structural units derived from a1,3-dihydroxybenzene organodicarboxylate are reported in Int. Pat. App.Pub. No. WO 2000/061664, and certain polymers containing resorcinolarylate polyester chain members are reported in U.S. Pat. No. 6,306,507.Block copolyestercarbonates comprising structural units derived from atleast one 1,3-dihydroxybenzene and at least one aromatic dicarboxylicacid formed into a layer and layered with another polymer comprisingcarbonate structural units are reported in US 2004/0253428. Weatherablefilms containing polycarbonate may have relatively high CTEs incomparison to polyesters, for example. The CTE of a second polymericfilm substrate containing a polycarbonate may be, for example, about 70ppm/K.

In some embodiments, the second polymeric film substrate useful forpracticing the present disclosure comprises a multilayer optical film.In some embodiments, the second polymeric film substrate comprises anultraviolet-reflective multilayer optical film having first and secondmajor surfaces and comprising an ultraviolet-reflective optical layerstack, where the ultraviolet-reflective optical layer stack comprisesfirst optical layers and second optical layers, wherein at least aportion of the first optical layers and at least a portion of the secondoptical layers are in intimate contact and have different refractiveindexes, and wherein the multilayer optical film further comprises aultraviolet absorber in at least one of the first optical layer, thesecond optical layer, or a third layer disposed on at least one of thefirst or second major surfaces of the ultraviolet reflectiver multilayeroptical film. In some embodiments, the multilayer optical film comprisesat least a plurality of first and second optical layers collectivelyreflecting at least 50 (in some embodiments, at least 55, 60, 65, 70,75, 80, 85, 90, 95, 96, 97, or even at least 98) percent of incident UVlight over at least a 30 (in some embodiments, at least 35, 40, 45, 50,55, 60, 65, 70, 75, 80, 85, 90, 95, or even at least 100) nanometerwavelength range in a wavelength range from at least 300 nanometers to400 nanometers. In some embodiments, some of at least one of the firstor second optical layers (in some embodiments at least 50 percent bynumber of the first and/or second layers, in some embodiments all of atleast one of the first or second layers) comprises a UV absorber. Insome embodiments, the multilayer optical film comprises a third opticallayer having first and second generally opposed first and second majorsurfaces and absorbing at least 50 (in some embodiments, at least 55,60, 65, 70, 75, 80, 85, 90, or even at least 95) percent of incident UVlight over at least a 30 (in some embodiments, at least 35, 40, 45, 50,55, 60, 65, 70, 75, 80, 85, 90, 95, or even at least 100) nanometerwavelength range in a wavelength range from at least 300 nanometers to400 nanometers. In some embodiments, the major surface of the pluralityof first and second optical layers is proximate (i.e., not more than 1mm, in some embodiments, not more than 0.75 mm, 0.5 mm, 0.4, mm, 0.3 mm,0.25 mm, 0.2 mm, 0.15 mm, 0.1 mm, or even not greater than 0.05 mm; insome embodiments, contacting) to the first major surface of the thirdoptical layer. There may be or may not be another multilayer opticalfilm proximate the second surface of the third optical layer. In any ofthe aforementioned embodiments, the multilayer optical film may comprisea fourth optical layer comprising polyethylene naphthalate. In someembodiments, a plurality of the fourth optical layers collectivelyabsorb at least 50 (in some embodiments, at least 55, 60, 65, 70, 75,80, 85, 90, or even at least 95) percent of incident light over at least30, 35, 40, 45, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, 500,600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700,1800, 1900, 2000, or even 2100) nanometer wavelength range in awavelength range from 400 nanometers to 2500 nanometers.

For multilayer optical films described herein, the first and secondlayers (in some embodiments, alternating first and second opticallayers) of the multilayer optical films typically have a difference inrefractive index of at least 0.04 (in some embodiments, at least 0.05,0.06, 0.07, 0.08, 0.09, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25,0.275, or even at least 0.3). In some embodiments, the first opticallayer is birefringent and comprises a birefringent polymer. The layerthickness profile (layer thickness values) of multilayer optical filmdescribed herein reflecting at least 50 percent of incident UV lightover a specified wavelength range can be adjusted to be approximately alinear profile with the first (thinnest) optical layers adjusted to haveabout a ¼ wave optical thickness (index times physical thickness) for300 nm light and progressing to the thickest layers which would beadjusted to be about ¼ wave thick optical thickness for 420 nm light.Light that is not reflected at the interface between adjacent opticallayers typically passes through successive layers and is eitherreflected at a subsequent interface, passes through the UV-reflectiveoptical layer stack altogether, or may be absorbed by an absorbinglayer.

The normal reflectivity for a particular layer pair is primarilydependent on the optical thickness of the individual layers, whereoptical thickness is defined as the product of the actual thickness ofthe layer times its refractive index. The intensity of light reflectedfrom the optical layer stack is a function of its number of layer pairsand the differences in refractive indices of optical layers in eachlayer pair. The ratio n₁d₁/(n₁d₁+n₂d₂) (commonly termed the “f-ratio”)correlates with reflectivity of a given layer pair at a specifiedwavelength. In the f-ratio, n₁ and n₂ are the respective refractiveindexes at the specified wavelength of the first and second opticallayers in a layer pair, and d₁ and d₂ are the respective thicknesses ofthe first and second optical layers in the layer pair. By properselection of the refractive indexes, optical layer thicknesses, andf-ratio one can exercise some degree of control over the intensity offirst order reflection.

The equation λ/2=n₁d₁+n₂d₂ can be used to tune the optical layers toreflect light of wavelength λ at a normal angle of incidence. At otherangles, the optical thickness of the layer pair depends on the distancetraveled through the component optical layers (which is larger than thethickness of the layers) and the indices of refraction for at least twoof the three optical axes of the optical layer. The optical layers caneach be a quarter-wavelength thick or the optical thin layers can havedifferent optical thicknesses, as long as the sum of the opticalthicknesses is half of a wavelength (or a multiple thereof). An opticalstack having more than two layer pairs can include optical layers withdifferent optical thicknesses to provide reflectivity over a range ofwavelengths. For example, an optical stack can include layer pairs thatare individually tuned to achieve optimal reflection of normallyincident light having particular wavelengths or may include a gradientof layer pair thicknesses to reflect light over a larger bandwidth. Atypical approach is to use all or mostly quarter-wave film stacks. Inthis case, control of the spectrum requires control of the layerthickness profile in the film stack.

Desirable techniques for providing a multilayer optical film with acontrolled spectrum include the use of an axial rod heater control ofthe layer thickness values of coextruded polymer layers as described,for example, in U.S. Pat. No. 6,783,349 (Neavin et al.), the disclosureof which is incorporated herein by reference; timely layer thicknessprofile feedback during production from a layer thickness measurementtool such as an atomic force microscope (AFM), a transmission electronmicroscope, or a scanning electron microscope; optical modeling togenerate the desired layer thickness profile; and repeating axial rodadjustments based on the difference between the measured layer profileand the desired layer profile.

The basic process for layer thickness profile control involvesadjustment of axial rod zone power settings based on the difference ofthe target layer thickness profile and the measured layer profile. Theaxial rod power increase needed to adjust the layer thickness values ina given feedblock zone may first be calibrated in terms of watts of heatinput per nanometer of resulting thickness change of the layersgenerated in that heater zone. For example, fine control of the spectrumis possible using 24 axial rod zones for 275 layers. Once calibrated,the necessary power adjustments can be calculated once given a targetprofile and a measured profile. The procedure is repeated until the twoprofiles converge.

Exemplary materials for making the optical layers that reflect (e.g.,the first and second optical layers) include polymers and polymer blends(e.g., polyesters, copolyesters, modified copolyesters, andpolycarbonates). Polyesters can be made, for example, from ring-openingaddition polymerization of a lactone or by condensation of adicarboxylic acid (or derivative thereof such as a diacid halide or adiester) with a diol. The dicarboxylic acid or dicarboxylic acidderivative molecules may all be the same or there may be two or moredifferent types of molecules. The same applies to the diol monomermolecules. Polycarbonates can be made, for example, from the reaction ofdiols with esters of carbonic acid.

Examples of suitable dicarboxylic acid molecules for use in formingpolyesters include 2,6-naphthalene dicarboxylic acid and isomersthereof; terephthalic acid; isophthalic acid; phthalic acid; azelaicacid; adipic acid; sebacic acid; norbornanedicarboxylic acid;bicyclooctane dicarboxylic acid; 1,6-cyclohexanedicarboxylic acid andisomers thereof; t-butyl isophthalic acid, trimellitic acid, sodiumsulfonated isophthalic acid; 4,4′-biphenyl dicarboxylic acid and isomersthereof. Acid halides and lower alkyl esters of these acids, such asmethyl or ethyl esters, may also be used as functional equivalents. Theterm “lower alkyl” refers, in this context, to C1-C10 straight-chainedor branched alkyl groups. Examples of suitable diols for use in formingpolyesters include ethylene glycol; propylene glycol; 1,4-butanediol andisomers thereof; 1,6-hexanediol; neopentyl glycol; polyethylene glycol;diethylene glycol; tricyclodecanediol; 1,4-cyclohexanedimethanol andisomers thereof; norbornanediol; bicyclooctanediol; trimethylol propane;pentaerythritol; 1,4-benzenedimethanol and isomers thereof; bisphenol A;1,8-dihydroxy biphenyl and isomers thereof; and1,3-bis(2-hydroxyethoxy)benzene.

Exemplary birefringement polymers useful for the reflective layer(s)include polyethylene terephthalate (PET). Its refractive index forpolarized incident light of 550 nm wavelength increases when the planeof polarization is parallel to the stretch direction from about 1.57 toas high as about 1.69. Increasing molecular orientation increases thebirefringence of PET. The molecular orientation may be increased bystretching the material to greater stretch ratios and holding otherstretching conditions fixed. Copolymers of PET (CoPET), such as thosedescribed in U.S. Pat. No. 6,744,561 (Condo et al.) and U.S. Pat. No.6,449,093 (Hebrink et al.), the disclosures of which are incorporatedherein by reference, are particularly useful for their relatively lowtemperature (typically less than 250° C.) processing capability makingthem more coextrusion compatible with less thermally stable secondpolymers. Other semicrystalline polyesters suitable as birefringentpolymers include polybutylene 2,6-terephthalate (PBT), polyethyleneterephthalate (PET), and copolymers thereof such as those described inU.S. Pat. No. 6,449,093 B2 (Hebrink et al.) or U.S. Pat. Pub. No.20060084780 (Hebrink et al.), the disclosures of which are incorporatedherein by reference. Other useful birefringent polymers includesyndiotactic polystyrene (sPS); polyethylene 2,6-naphthalates (PENs);copolyesters derived from naphthalenedicarboxylic acid, an additionaldicarboxylic acid, and a diol (coPENs) (e.g., a polyester derivedthrough co-condensation of 90 equivalents of dimethylnaphthalenedicarboxylate, 10 equivalents of dimethyl terephthalate, and100 equivalents of ethylene glycol, and having an intrinsic viscosity(IV) of 0.48 dL/g, and an index of refraction is approximately 1.63);polyether imides; and polyester/non-polyester combinations; polybutylene2,6-naphthalates (PBNs); modified polyolefin elastomers, e.g., asavailable as ADMER (e.g., ADMER SE810) thermoplastic elastomers fromMitsui Chemicals America, Inc. of Rye Brook, N.Y.; and thermoplasticpolyurethanes (TPUs) (e.g., as available as ELASTOLLAN TPUs from BASFCorp. of Florham Park, N.J. and as TECOFLEX or STATRITE TPUs (e.g.,STATRITE X5091 or STATRITE M809) from The Lubrizol Corp. of Wickliffe,Ohio).

Further, for example, the second polymer (layer) of the multilayeroptical film can be made from a variety of polymers having glasstransition temperatures compatible with that of the first layer andhaving a refractive index similar to the isotropic refractive index ofthe birefringent polymer. Examples of other polymers suitable for use inoptical films and, particularly, in the second polymer include vinylpolymers and copolymers made from monomers such as vinyl naphthalenes,styrene, maleic anhydride, acrylates, and methacrylates. Examples ofsuch polymers include polyacrylates, polymethacrylates, such aspoly(methyl methacrylate) (PMMA), and isotactic or syndiotacticpolystyrene. Other polymers include condensation polymers such aspolysulfones, polyamides, polyurethanes, polyamic acids, and polyimides.In addition, the second polymer can be formed from homopolymers andcopolymers of polyesters, polycarbonates, fluoropolymers, andpolydimethylsiloxanes, and blends thereof.

Many exemplary polymers for the optical layers, especially for use inthe second layer, are commercially available and include homopolymers ofpolymethylmethacrylate (PMMA), such as those available from IneosAcrylics, Inc., Wilmington, Del., under the trade designations “CP71”and “CP80;” and polyethyl methacrylate (PEMA), which has a lower glasstransition temperature than PMMA. Additional useful polymers includecopolymers of PMMA (CoPMMA), such as a CoPMMA made from 75 wt %methylmethacrylate (MMA) monomers and 25 wt % ethyl acrylate (EA)monomers, (available from Ineos Acrylics, Inc., under the tradedesignation “PERSPEX CP63” or Arkema, Philadelphia, Pa., under the tradedesignation “ATOGLAS 510”), a CoPMMA formed with MMA comonomer units andn-butyl methacrylate (nBMA) comonomer units, or a blend of PMMA andpoly(vinylidene fluoride) (PVDF). Additional suitable polymers for theoptical layers, especially for use in the second layer, includepolyolefin copolymers such as poly(ethylene-co-octene) (PE-PO) availablefrom Dow Elastomers, Midland, Mich., under the trade designation “ENGAGE8200,” poly(propylene-co-ethylene) (PPPE) available from AtofinaPetrochemicals, Inc., Houston, Tex., under the trade designation“Z9470,” and a copolymer of atactic polypropylene (aPP) and isotatcticpolypropylene (iPP). The multilayer optical films can also include, forexample, in the second layers, a functionalized polyolefin, such aslinear low density polyethylene-g-maleic anhydride (LLDPE-g-MA) such asthat available from E.I. duPont de Nemours & Co., Inc., under the tradedesignation “BYNEL 4105.”

The third optical layer, if present, comprises a polymer and aUV-absorber and can serve as a UV protective layer. Typically, thepolymer is a thermoplastic polymer. Examples of suitable polymersinclude polyesters (e.g., polyethylene terephthalate), fluoropolymers,acrylics (e.g., polymethyl methacrylate), silicone polymers (e.g.,thermoplastic silicone polymers), styrenic polymers, polyolefins,olefinic copolymers (e.g., copolymers of ethylene and norborneneavailable as “TOPAS COC” from Topas Advanced Polymers of Florence, Ky.),silicone copolymers, and combinations thereof (e.g., a blend ofpolymethyl methacrylate and polyvinylidene fluoride).

Exemplary polymer compositions for the third layer and/or second layersin alternating layers with the at least one birefringent polymer includePMMA, CoPMMA, polydimethyl siloxane oxamide based segmented copolymer(SPDX), fluoropolymers including homopolymers such as PVDF andcopolymers such as those derived from tetrafluoroethylene,hexafluoropropylene, and vinylidene fluoride (THV), blends of PVDF/PMMA,acrylate copolymers, styrene, styrene copolymers, silicone copolymers,polycarbonate, polycarbonate copolymers, polycarbonate blends, blends ofpolycarbonate and styrene maleic anhydride, and cyclic-olefincopolymers.

The selection of the polymer combinations used in creating themultilayer optical film depends, for example, upon the desired bandwidththat will be reflected. Higher refractive index differences between thebirefringent polymer and the second polymer create more optical powerthus enabling more reflective bandwidth. Alternatively, additionallayers may be employed to provide more optical power. Preferredcombinations of birefringent layers and second polymer layers mayinclude, for example, the following: PET/THV, PET/SPDX, PEN/THV,PEN/SPDX, PEN/PMMA, PET/CoPMMA, PEN/CoPMMA, CoPEN/PMMA, CoPEN/SPDX,sPS/SPDX, sPS/THV, CoPEN/THV, PET/fluoroelastomers, sPS/fluoroelastomersand CoPEN/fluoroelastomers. The CTE of the multilayer optical film istypically a weighted average of the first polymer layers, second polymerlayers, and any other polymer layers. In some embodiments, when amultilayer optical film is selected as the second polymeric filmsubstrate, the CTE mismatch between the first and second polymeric filmsubstrates is less than 40 ppm/K.

In some embodiments, material combinations for making the optical layersthat reflect UV light (e.g., the first and second optical layers)include PMMA and THV and PET and CoPMMA. Exemplary material for makingthe optical layers that absorb UV light (e.g., the third optical layer)include PET, CoPMMA, or blends of PMMA and PVDF.

A UV absorbing layer (e.g., a UV protective layer) aids in protectingthe visible/IR-reflective optical layer stack from UV-light causeddamage/degradation over time by absorbing UV-light (preferably anyUV-light) that may pass through the UV-reflective optical layer stack.In general, the UV-absorbing layer(s) may include any polymericcomposition (i.e., polymer plus additives) that is capable ofwithstanding UV-light for an extended period of time. A variety ofoptional additives may be incorporated into an optical layer to make itUV absorbing. Examples of such additives include at least one of UVabsorbers (UVAs), HALS, or anti-oxidants. Typical UV absorbing layershave thicknesses in a range from 13 micrometers to 380 micrometers (0.5mil to 15 mil) with a UVA loading level of 2-10% by weight.

A UVA is typically a compound capable of absorbing or blockingelectromagnetic radiation at wavelengths less than 400 nm whileremaining substantially transparent at wavelengths greater than 400 nm.Such compounds can intervene in the physical and chemical processes ofphotoinduced degradation. UVAs are typically included in a UV absorbinglayer in an amount sufficient to absorb at least 70% (in someembodiments, at least 80%, or greater than 90% of the UV light in thewavelength region from 180 nm to 400 nm). Typically, it is desirable ifthe UVA is highly soluble in polymers, highly absorptive,photo-permanent and thermally stable in the temperature range from 200°C. to 300° C. for extrusion processes to form the protective layer. TheUVA can also be highly suitable if they can be copolymerizable withmonomers to form protective coating layer by UV curing, gamma raycuring, e-beam curing, or thermal curing processes.

Red-shifted UVAs (RUVAs) typically have enhanced spectral coverage inthe long-wave UV region, enabling it to block the high wavelength UVlight that can cause yellowing in polyesters. One of the most effectiveRUVAs is a benzotriazole compound,5-trifluoromethyl-2-(2-hydroxy-3-alpha-cumyl-5-tert-octylphenyl)-2H-benzotriazole(sold under the trade designation “CGL-0139” from Ciba SpecialtyChemicals Corporation, Tarryton, N.Y.). Other exemplary benzotriazolesinclude 2-(2-hydroxy-3,5-di-alpha-cumylphenyl)-2H-benzotriazole,5-chloro-2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzothiazole,5-chloro-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole,2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole,2-(2-hydroxy-3-alpha-cumyl-5-tert-octylphenyl)-2H-benzotriazole,2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2Hbenzotriazole.Further exemplary RUVA includes2(−4,6-diphenyl-1-3,5-triazin-2-yl)-5-henyloxy-phenol. Other exemplaryUV absorbers include those available from Ciba Specialty ChemicalsCorporation under the trade designation “TINUVIN 1577,” “TINUVIN 900,”and “TINUVIN 777.” Another exemplary UV absorber is available in apolyester master batch from Sukano Polymers Corporation, Dunkin S.C.,under the trade designation “TA07-07MB”. Another exemplary UV absorberis available in a polycarbonate master batch from Sukano PolymersCorporation under the trade designation “TA28-09 MB”. In addition, theUV absorbers can be used in combination with hindered amine lightstabilizers (HALS) and anti-oxidants. Exemplary HALS include thoseavailable from Ciba Specialty Chemicals Corporation, under the tradedesignation “CHIMASSORB 944” and “TINUVIN 123.” Exemplary anti-oxidantsinclude those obtained under the trade designations “IRGAFOS 126”,“IRGANOX 1010” and “ULTRANOX 626”, also available from Ciba SpecialtyChemicals Corporation.

The desired thickness of a UV protective layer is typically dependentupon an optical density target at specific wavelengths as calculated byBeers Law. In some embodiments, the UV protective layer has an opticaldensity greater than 3.5, 3.8, or 4 at 380 nm; greater than 1.7 at 390nm; and greater than 0.5 at 400 nm. Those of ordinary skill in the artrecognize that the optical densities typically should remain fairlyconstant over the extended life of the film in order to provide theintended protective function.

The UV protective layer and any optional additives may be selected toachieve the desired protective functions such as UV protection. Those ofordinary skill in the art recognize that there are multiple means forachieving the noted objectives of the UV protective layer. For example,additives that are very soluble in certain polymers may be added to thecomposition. Of particular importance, is the permanence of theadditives in the polymer. The additives should not degrade or migrateout of the polymer. Additionally, the thickness of the layer may bevaried to achieve desired protective results. For example, thicker UVprotective layers would enable the same UV absorbance level with lowerconcentrations of UV absorbers, and would provide more UV absorberpermanence attributed to less driving force for UV absorber migration.

For additional details on multilayer optical films that may be useful assecond polymeric film substrates (e.g., UV mirrors), see, for example,International Patent Application Publication Nos. WO 2010/078105(Hebrink et al.) and WO 2011/062836 (Hebrink et al.), the disclosures ofwhich are incorporated herein by reference.

For any of the embodiments of the second polymeric film substratedescribed above, the major surface of the second polymeric filmsubstrate (e.g., fluoropolymer) can be treated to improve adhesion tothe PSA. Useful surface treatments include electrical discharge in thepresence of a suitable reactive or non-reactive atmosphere (e.g.,plasma, glow discharge, corona discharge, dielectric barrier dischargeor atmospheric pressure discharge); chemical pretreatment (e.g., usingalkali solution and/or liquid ammonia); flame pretreatment; or electronbeam treatment. A separate adhesion promotion layer may also be formedbetween the major surface of the second polymeric film substrate and thePSA. In some embodiments, the second polymeric film substrate may be afluoropolymer that has been coated with a PSA and subsequentlyirradiated with an electron beam to form a chemical bond between thesubstrate and the pressure sensitive adhesive; (see, e.g., U.S. Pat. No.6,878,400 (Yamanaka et al.). Some useful second polymeric filmsubstrates that are surface treated are commercially available, forexample, from St. Gobain Performance Plastics under the tradedesignation “NORTON ETFE”.

In some embodiments, the second polymeric film substrate has a thicknessfrom about 0.01 mm to about 1 mm, in some embodiments, from about 0.05mm to about 0.25 mm or from 0.05 mm to 0.15 mm. Thicknesses outsidethese ranges may also be useful, depending on the application. Inembodiments wherein the CTE of the second polymeric film substrate ismore than 40 ppm/K higher than the CTE of the first polymeric filmsubstrate, the thickness of the second polymeric film substrate may beminimized to minimize the effect of the higher CTE. For example, thethickness of the second polymeric film substrate may be up to 0.2, 0.18,0.16, 0.14, 0.13, or 0.12 mm.

While the second polymeric film substrate useful for practicing thepresent disclosure has excellent outdoor stability, barrier films arerequired in the assemblies disclosed herein to reduce the permeation ofwater vapor to levels that allow its use in long term outdoorapplications such as building integrated photovoltaic's (BIPV).

Barrier Film

Barrier films 120, 320 useful for practicing the present disclosure canbe selected from a variety of constructions. The term “barrier film”refers to films that provide a barrier to at least one of oxygen orwater. Barrier films are typically selected such that they have oxygenand water transmission rates at a specified level as required by theapplication. In some embodiments, the barrier film has a water vaportransmission rate (WVTR) less than about 0.005 g/m²/day at 38° C. and100% relative humidity; in some embodiments, less than about 0.0005g/m²/day at 38° C. and 100% relative humidity; and in some embodiments,less than about 0.00005 g/m²/day at 38° C. and 100% relative humidity.In some embodiments, the flexible barrier film has a WVTR of less thanabout 0.05, 0.005, 0.0005, or 0.00005 g/m²/day at 50° C. and 100%relative humidity or even less than about 0.005, 0.0005, 0.00005g/m²/day at 85° C. and 100% relative humidity. In some embodiments, thebarrier film has an oxygen transmission rate of less than about 0.005g/m²/day at 23° C. and 90% relative humidity; in some embodiments, lessthan about 0.0005 g/m²/day at 23° C. and 90% relative humidity; and insome embodiments, less than about 0.00005 g/m²/day at 23° C. and 90%relative humidity.

Exemplary useful barrier films include inorganic films prepared byatomic layer deposition, thermal evaporation, sputtering, and chemicalvapor deposition. Useful barrier films are typically flexible andtransparent.

In some embodiments, useful barrier films comprise inorganic/organicmultilayers (e.g., 228, 226, 224 and 428, 426, 424). Flexibleultra-barrier films comprising inorganic/organic multilayers aredescribed, for example, in U.S. Pat. No. 7,018,713 (Padiyath et al.).Such flexible ultra-barrier films may have a first polymer layer 224disposed on polymeric film substrate 240 that is overcoated with two ormore inorganic barrier layers 226 separated by at least one secondpolymer layer 228. In some embodiments, the barrier film comprises oneinorganic barrier layer 226 interposed between the first polymer layer224 disposed on the polymeric film substrate 240 and a second polymerlayer 228.

The first and second polymer layers 224 and 228 can independently beformed by applying a layer of a monomer or oligomer and crosslinking thelayer to form the polymer in situ, for example, by flash evaporation andvapor deposition of a radiation-crosslinkable monomer followed bycrosslinking, for example, using an electron beam apparatus, UV lightsource, electrical discharge apparatus or other suitable device. Thefirst polymer layer 224 is applied, for example, to the first polymericfilm substrate 240, and the second polymer layer is typically applied tothe inorganic barrier layer. The materials and methods useful forforming the first and second polymer layers may be independentlyselected to be the same or different. Useful techniques for flashevaporation and vapor deposition followed by crosslinking in situ can befound, for example, in U.S. Pat. Nos. 4,696,719 (Bischoff), 4,722,515(Ham), 4,842,893 (Yializis et al.), 4,954,371 (Yializis), 5,018,048(Shaw et al.), 5,032,461(Shaw et al.), 5,097,800 (Shaw et al.),5,125,138 (Shaw et al.), 5,440,446 (Shaw et al.), 5,547,908 (Furuzawa etal.), 6,045,864 (Lyons et al.), 6,231,939 (Shaw et al.) and 6,214,422(Yializis); in published PCT Application No. WO 00/26973 (Delta VTechnologies, Inc.); in D. G. Shaw and M. G. Langlois, “A New VaporDeposition Process for Coating Paper and Polymer Webs”, 6thInternational Vacuum Coating Conference (1992); in D. G. Shaw and M. G.Langlois, “A New High Speed Process for Vapor Depositing Acrylate ThinFilms: An Update”, Society of Vacuum Coaters 36th Annual TechnicalConference Proceedings (1993); in D. G. Shaw and M. G. Langlois, “Use ofVapor Deposited Acrylate Coatings to Improve the Barrier Properties ofMetallized Film”, Society of Vacuum Coaters 37th Annual TechnicalConference Proceedings (1994); in D. G. Shaw, M. Roehrig, M. G. Langloisand C. Sheehan, “Use of Evaporated Acrylate Coatings to Smooth theSurface of Polyester and Polypropylene Film Substrates”, RadTech (1996);in J. Affinito, P. Martin, M. Gross, C. Coronado and E. Greenwell,“Vacuum deposited polymer/metal multilayer films for opticalapplication”, Thin Solid Films 270, 43-48 (1995); and in J. D. Affinito,M. E. Gross, C. A. Coronado, G. L. Graff, E. N. Greenwell and P. M.Martin, “Polymer-Oxide Transparent Barrier Layers”, Society of VacuumCoaters 39th Annual Technical Conference Proceedings (1996). In someembodiments, the polymer layers and inorganic barrier layer aresequentially deposited in a single pass vacuum coating operation with nointerruption to the coating process.

The coating efficiency of the first polymer layer 224 can be improved,for example, by cooling the polymeric film substrate 240. Similartechniques can also be used to improve the coating efficiency of thesecond polymer layer 228. The monomer or oligomer useful for forming thefirst and/or second polymer layers can also be applied usingconventional coating methods such as roll coating (e.g., gravure rollcoating) or spray coating (e.g., example, electrostatic spray coating).The first and/second polymer layers can also be formed by applying alayer containing an oligomer or polymer in solvent and then removing thesolvent using conventional techniques (e.g., at least one of heat orvacuum). Plasma polymerization may also be employed.

Volatilizable acrylate and methacrylate monomers are useful for formingthe first and second polymer layers. In some embodiments, volatilizableacrylates are used. Volatilizable acrylate and methacrylate monomers mayhave a molecular weight in the range from about 150 to about 600 gramsper mole, or, in some embodiments, from about 200 to about 400 grams permole. In some embodiments, volatilizable acrylate and methacrylatemonomers have a value of the ratio of the molecular weight to the numberof (meth)acrylate functional groups per molecule in the range from about150 to about 600 g/mole/(meth)acrylate group, in some embodiments, fromabout 200 to about 400 g/mole/(meth)acrylate group. Fluorinatedacrylates and methacrylates can be used at higher molecular weightranges or ratios, for example, about 400 to about 3000 molecular weightor about 400 to about 3000 g/mole/(meth)acrylate group. Exemplary usefulvolatilizable acrylates and methacrylates include hexanediol diacrylate,ethoxyethyl acrylate, phenoxyethyl acrylate, cyanoethyl(mono)acrylate,isobornyl acrylate, isobornyl methacrylate, octadecyl acrylate, isodecylacrylate, lauryl acrylate, beta-carboxyethyl acrylate,tetrahydrofurfuryl acrylate, dinitrile acrylate, pentafluorophenylacrylate, nitrophenyl acrylate, 2-phenoxyethyl acrylate, 2-phenoxyethylmethacrylate, 2,2,2-trifluoromethyl(meth)acrylate, diethylene glycoldiacrylate, triethylene glycol diacrylate, triethylene glycoldimethacrylate, tripropylene glycol diacrylate, tetraethylene glycoldiacrylate, neopentyl glycol diacrylate, propoxylated neopentyl glycoldiacrylate, polyethylene glycol diacrylate, tetraethylene glycoldiacrylate, bisphenol A epoxy diacrylate, 1,6-hexanediol dimethacrylate,trimethylol propane triacrylate, ethoxylated trimethylol propanetriacrylate, propylated trimethylol propane triacrylate,tris(2-hydroxyethyl)isocyanurate triacrylate, pentaerythritoltriacrylate, phenylthioethyl acrylate, naphthloxyethyl acrylate, cyclicdiacrylates (for example, EB-130 from Cytec Industries Inc. andtricyclodecane dimethanol diacrylate, available as SR833S from SartomerCo.), epoxy acrylate RDX80095 from Cytec Industries Inc., and mixturesthereof.

Useful monomers for forming the first and second polymer layers areavailable from a variety of commercial sources and include urethaneacrylates (e.g., available from Sartomer Co., Exton, Pa. under the tradedesignations “CN-968” and “CN-983”), isobornyl acrylate (e.g., availablefrom Sartomer Co. under the trade designation “SR-506”),dipentaerythritol pentaacrylates (e.g., available from Sartomer Co.under the trade designation “SR-399”), epoxy acrylates blended withstyrene (e.g., available from Sartomer Co. under the trade designation“CN-120S80”), di-trimethylolpropane tetraacrylates (e.g., available fromSartomer Co. under the trade designation “SR-355”), diethylene glycoldiacrylates (e.g., available from Sartomer Co. under the tradedesignation “SR-230”), 1,3-butylene glycol diacrylate (e.g., availablefrom Sartomer Co. under the trade designation “SR-212”), pentaacrylateesters (e.g., available from Sartomer Co. under the trade designation“SR-9041”), pentaerythritol tetraacrylates (e.g., available fromSartomer Co. under the trade designation “SR-295”), pentaerythritoltriacrylates (e.g., available from Sartomer Co. under the tradedesignation “SR-444”), ethoxylated (3) trimethylolpropane triacrylates(e.g., available from Sartomer Co. under the trade designation“SR-454”), ethoxylated (3) trimethylolpropane triacrylates (e.g.,available from Sartomer Co. under the trade designation “SR-454HP”),alkoxylated trifunctional acrylate esters (e.g., available from SartomerCo. under the trade designation “SR-9008”), dipropylene glycoldiacrylates (e.g., available from Sartomer Co. under the tradedesignation “SR-508”), neopentyl glycol diacrylates (e.g., availablefrom Sartomer Co. under the trade designation “SR-247”), ethoxylated(4)bisphenol a dimethacrylates (e.g., available from Sartomer Co. underthe trade designation “CD-450”), cyclohexane dimethanol diacrylateesters (e.g., available from Sartomer Co. under the trade designation“CD-406”), isobornyl methacrylate (e.g., available from Sartomer Co.under the trade designation “SR-423”), cyclic diacrylates (e.g.,available from UCB Chemical, Smyrna, Ga., under the trade designation“IRR-214”) and tris(2-hydroxy ethyl) isocyanurate triacrylate (e.g.,available from Sartomer Co. under the trade designation “SR-368”),acrylates of the foregoing methacrylates and methacrylates of theforegoing acrylates.

Other monomers that are useful for forming the first and/or secondpolymer layers include vinyl ethers, vinyl naphthylene, acrylonitrile,and mixtures thereof.

The desired chemical composition and thickness of the first polymerlayer 224 will depend in part on the nature and surface topography ofthe polymeric film substrate 240. The thickness of the first and/orsecond polymer layers will typically be sufficient to provide a smooth,defect-free surface to which inorganic barrier layer 226 can be appliedsubsequently. For example, the first polymer layer may have a thicknessof a few nm (for example, 2 or 3 nm) to about 5 micrometers or more. Thethickness of the second polymer layer may also be in this range and may,in some embodiments, be thinner than the first polymer layer.

Inorganic barrier layer 226 can be formed from a variety of materials.Useful materials include metals, metal oxides, metal nitrides, metalcarbides, metal oxynitrides, metal oxyborides, and combinations thereof.Exemplary metal oxides include silicon oxides such as silica, aluminumoxides such as alumina, titanium oxides such as titania, indium oxides,tin oxides, indium tin oxide (ITO), tantalum oxide, zirconium oxide,niobium oxide, and combinations thereof. Other exemplary materialsinclude boron carbide, tungsten carbide, silicon carbide, aluminumnitride, silicon nitride, boron nitride, aluminum oxynitride, siliconoxynitride, boron oxynitride, zirconium oxyboride, titanium oxyboride,and combinations thereof. In some embodiments, the inorganic barrierlayer comprises at least one of ITO, silicon oxide, or aluminum oxide.In some embodiments, with the proper selection of the relativeproportions of each elemental constituent, ITO can be electricallyconductive. The inorganic barrier layers can be formed, for example,using techniques employed in the film metabolizing art such assputtering (for example, cathode or planar magnetron sputtering, dual ACplanar magnetron sputtering or dual AC rotatable magnetron sputtering),evaporation (for example, resistive or electron beam evaporation andenergy enhanced analogs of resistive or electron beam evaporationincluding ion beam and plasma assisted deposition), chemical vapordeposition, plasma-enhanced chemical vapor deposition, and plating. Insome embodiments, the inorganic barrier layers are formed usingsputtering, for example, reactive sputtering. Enhanced barrierproperties may be observed when the inorganic layer is formed by a highenergy deposition technique such as sputtering compared to lower energytechniques such as conventional vapor deposition processes. Withoutbeing bound by theory, it is believed that the enhanced properties aredue to the condensing species arriving at the substrate with greaterkinetic energy, leading to a lower void fraction as a result ofcompaction.

The desired chemical composition and thickness of each inorganic barrierlayer will depend in part on the nature and surface topography of theunderlying layer and on the desired optical properties for the barrierfilm. The inorganic barrier layers typically are sufficiently thick soas to be continuous, and sufficiently thin so as to ensure that thebarrier films and assemblies disclosed herein will have the desireddegree of visible light transmission and flexibility. The physicalthickness (as opposed to the optical thickness) of each inorganicbarrier layer may be, for example, about 3 nm to about 150 nm (in someembodiments, about 4 nm to about 75 nm). The inorganic barrier layertypically has an average transmission over the visible portion of thespectrum of at least about 75% (in some embodiments at least about 80,85, 90, 92, 95, 97, or 98%) measured along the normal axis. In someembodiments, the inorganic barrier layer has an average transmissionover a range of 400 nm to 1400 nm of at least about 75% (in someembodiments at least about 80, 85, 90, 92, 95, 97, or 98%). Usefulinorganic barrier layers typically are those that do not interfere withabsorption of visible or infrared light, for example, by photovoltaiccells.

Additional inorganic barrier layers and polymer layers can be present ifdesired. In embodiments wherein more than one inorganic barrier layer ispresent, the inorganic barrier layers do not have to be the same or havethe same thickness. When more than one inorganic barrier layer ispresent, the inorganic barrier layers can respectively be referred to asthe “first inorganic barrier layer” and “second inorganic barrierlayer”. Additional “polymer layers” may be present in between additionalinorganic barrier layers. For example, the barrier film may have severalalternating inorganic barrier layers and polymer layers. Each unit ofinorganic barrier layer combined with a polymer layer is referred to asa dyad, and the barrier film can include any number of dyads. It canalso include various types of optional layers between the dyads.

Surface treatments or tie layers can be applied between any of thepolymer layers or inorganic barrier layers, for example, to improvesmoothness or adhesion. Useful surface treatments include electricaldischarge in the presence of a suitable reactive or non-reactiveatmosphere (e.g., plasma, glow discharge, corona discharge, dielectricbarrier discharge or atmospheric pressure discharge); chemicalpretreatment; or flame pretreatment. Exemplary useful tie layers includea separate polymeric layer or a metal-containing layer such as a layerof metal, metal oxide, metal nitride or metal oxynitride. The tie layermay have a thickness of a few nanometers (nm) (e.g., 1 or 2 nm) to about50 nm or more.

In some embodiments, one of the polymer layers (e.g., the top layer) inthe barrier film can be formed from co-depositing a silane (e.g., anamino silane or cyclic azasilane) and a radiation-curable monomer (e.g.,any of the acrylates listed above). Co-depositing includesco-evaporating and evaporating a mixture of the silane and the monomer.Cyclic azasilanes are ring compounds, wherein at least one of the ringmembers is a nitrogen and at least one of the ring members is a silicon,and wherein the ring contains at least one nitrogen-to-silicon bond. Insome embodiments, the cyclic azasilane is represented by the generalformula

In other embodiments, the cyclic azasilane is represented by the generalformula

In either of these embodiments, each R is independently alkyl having upto 12, 6, 4, 3, or 2 carbon atoms and R′ is hydrogen, alkyl, or alkenylwith alkyl and alkenyl each having up to 12, 6, 4, 3, or 2 carbon atomsand optionally substituted by amino. Exemplary cyclic azasilanes include2,2-dimethoxy-N-butyl-1-aza-2-silacyclopentane,2-methyl-2-methoxy-N-(2-aminoethyl)-1-aza-2-silacyclopentane,2,2-diethoxy-N-(2-aminoethyl)-1-aza-2-silacyclopentane,2,2-dimethyl-N-allyl-1-aza-2-silacyclopentane,2,2-dimethoxy-N-methyl-1-aza-2-silacyclopentane,2,2-diethoxy-1-aza-2-silacyclopentane,2,2-dimethoxy-1,6-diaza-2-silacyclooctane, andN-methyl-1-aza-2,2,4-trimethylsilacyclopentane. When the cyclicazasilane is placed in the presence of a hydroxyl (e.g., silanol) groupit quickly reacts to form a Si—O—Si (siloxane) linkage from the oxidesurface to the co-condensed pre-polymer while the nitrogen moietybecomes a reactive amine on the other end of the molecule that can bondwith pre-polymer compound(s) during polymerization. Amino silanes, whichhave the general formula Z₂N-L-SiY_(x)Y′_(3-x), wherein each Z isindependently hydrogen or alkyl having up to 12 carbon atoms, L isalkylene having up to 12 carbon atoms, x is 1, 2, or 3, Y is ahydrolysable group (e.g., alkoxy having up to 12 carbon atoms orhalogen), and Y′ is a non-hydrolysable group (e.g., alkyl having up to12 carbon atoms), have silane groups capable of forming siloxane bondswith a metal oxide surface and amino groups capable of reacting withpolymerizable compounds (e.g., acrylates). Exemplary amino silanesinclude (e.g., 3-aminopropyltrimethoxysilane;3-aminopropyltriethoxysilane;3-(2-aminoethyl)aminopropyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,bis-(gamma-triethoxysilylpropyl)amine;N-(2-aminoethyl)-3-aminopropyltributoxysilane;6-(aminohexylaminopropyl)trimethoxysilane; 4-aminobutyltrimethoxysilane;4-aminobutyltriethoxysilane;3-aminopropyltris(methoxyethoxyethoxy)silane;3-aminopropylmethyldiethoxysilane;3-(N-methylamino)propyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane;N-(2-aminoethyl)-3-aminopropyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropyltriethoxysilane;3-aminopropylmethyldiethoxysilane; 3-aminopropylmethyldimethoxysilane;3-aminopropyldimethylmethoxysilane; and3-aminopropyldimethylethoxysilane). Accordingly, in some embodiments,the barrier film comprises an inorganic layer that shares a chemicalbond (e.g., a siloxane bond) with one or more organic layers. Forexample, a hydroxyl group derived from a metal oxide can react with asilane group on an amino silane or cyclic azasilane. The amount of watervapor present in a multi-process vacuum chamber, for example, can becontrolled to promote the formation of such hydroxyl groups in highenough surface concentration to provide increased bonding sites. Withresidual gas monitoring and the use of water vapor sources, for example,the amount of water vapor in a vacuum chamber can be controlled toensure adequate generation of hydroxyl (e.g., Si—OH) groups.

With the addition of silanes, the peel strength of the coating isgreatly improved and peel strength adhesion is retained after exposureto high heat and humidity conditions. Additionally, the addition ofsilane eliminates the need for a tie layer, which greatly simplifies thecoating process and barrier coating stack construction. The resultingbarrier coatings retain high barrier properties and optical transmissionperformance. For additional details on barrier films containing cyclicazasilanes, see, for example, co-pending application having U.S. Ser.No. 12/829,525, filed on Jul. 2, 2010, the disclosure of which isincorporated by reference herein in its entirety.

In some embodiments, useful barrier films comprise plasma depositedpolymer layers (for example, diamond-like layers) such as thosedisclosed in U.S. Pat. App. Pub. No. 2007-0020451 (Padiyath et al.). Forexample, barrier films can be made by overcoating a first polymer layeron the polymeric film substrate, and a plasma deposited polymer layerovercoated on the first polymer layer. The first polymer layer may be asdescribed in any of the above embodiments of the first polymer layer.The plasma deposited polymer layer may be, for example, a diamond-likecarbon layer or a diamond-like glass. The term “overcoated” to describethe position of a layer with respect to a substrate or other element ofa barrier film, refers to the layer as being atop the substrate or otherelement, but not necessarily contiguous to either the substrate or theother element. The term “diamond-like glass” (DLG) refers tosubstantially or completely amorphous glass including carbon andsilicon, and optionally including one or more additional componentsselected from the group including hydrogen, nitrogen, oxygen, fluorine,sulfur, titanium, and copper. Other elements may be present in certainembodiments. The amorphous diamond-like glass films may containclustering of atoms to give it a short-range order but are essentiallydevoid of medium and long range ordering that lead to micro or macrocrystallinity, which can adversely scatter radiation having wavelengthsof from 180 nm to 800 nm. The term “diamond-like carbon” (DLC) refers toan amorphous film or coating comprising approximately 50 to 90 atomicpercent carbon and approximately 10 to 50 atomic percent hydrogen, witha gram atom density of between approximately 0.20 and approximately 0.28gram atoms per cubic centimeter, and composed of approximately 50% toapproximately 90% tetrahedral bonds.

In some embodiments, the barrier film can have multiple layers made fromalternating DLG or DLC layers and polymer layers (e.g., first and secondpolymer layers as described above) overcoated on the polymeric filmsubstrate. Each unit including a combination of a polymer layer and aDLG or DLC layer is referred to as a dyad, and the assembly can includeany number of dyads. It can also include various types of optionallayers between the dyads. Adding more layers in the barrier film mayincrease its imperviousness to oxygen, moisture, or other contaminantsand may also help cover or encapsulate defects within the layers.

In some embodiments, the diamond-like glass comprises, on ahydrogen-free basis, at least 30% carbon, a substantial amount ofsilicon (typically at least 25%) and no more than 45% oxygen. The uniquecombination of a fairly high amount of silicon with a significant amountof oxygen and a substantial amount of carbon makes these films highlytransparent and flexible. Diamond-like glass thin films may have avariety of light transmissive properties. Depending upon thecomposition, the thin films may have increased transmissive propertiesat various frequencies. However, in some embodiments, the thin film(when approximately one micron thick) is at least 70% transmissive toradiation at substantially all wavelengths from about 250 nm to about800 nm (e.g., 400 nm to about 800 nm). A transmission of 70% for a onemicron thick film corresponds to an extinction coefficient (k) of lessthan 0.02 in the visible wavelength range between 400 nm and 800 nm.

In creating a diamond-like glass film, various additional components canbe incorporated to alter and enhance the properties that thediamond-like glass film imparts to the substrate (for example, barrierand surface properties). The additional components may include one ormore of hydrogen, nitrogen, fluorine, sulfur, titanium, or copper. Otheradditional components may also be of benefit. The addition of hydrogenpromotes the formation of tetrahedral bonds. The addition of fluorinemay enhance barrier and surface properties of the diamond-like glassfilm, including the ability to be dispersed in an incompatible matrix.Sources of fluorine include compounds such as carbon tetrafluoride(CF₄), sulfur hexafluoride (SF₆), C₂F₆, C₃F₈, and C₄F₁₀. The addition ofnitrogen may be used to enhance resistance to oxidation and to increaseelectrical conductivity. Sources of nitrogen include nitrogen gas (N₂),ammonia (NH₃), and hydrazine (N₂H₆). The addition of sulfur can enhanceadhesion. The addition of titanium tends to enhance adhesion anddiffusion and barrier properties.

Various additives to the DLC film can be used. In addition to nitrogenor fluorine, which may be added for the reasons described above withregard to diamond-like glass, oxygen and silicon may be added. Theaddition of silicon and oxygen to the DLC coating tend to improve theoptical transparency and thermal stability of the coating. Sources ofoxygen include oxygen gas (O₂), water vapor, ethanol, and hydrogenperoxide. Sources of silicon preferably include silanes such as SiH₄,Si₂H₆, and hexamethyldisiloxane.

Additives to DLG or DLC films described above may be incorporated intothe diamond-like matrix or attached to the surface atomic layer. If theadditives are incorporated into the diamond-like matrix they may causeperturbations in the density and/or structure, but the resultingmaterial is essentially a densely packed network with diamond-likecarbon characteristics (e.g., chemical inertness, hardness, and barrierproperties). If the additive concentration is too large (e.g., greaterthan 50 atomic percent relative to the carbon concentration) the densitywill be affected and the beneficial properties of the diamond-likecarbon network will be lost. If the additives are attached to thesurface atomic layers they will alter only the surface structure andproperties. The bulk properties of the diamond-like carbon network willbe preserved.

Plasma deposited polymers such as diamond-like glass and diamond-likecarbon can be synthesized from a plasma by using precursor monomers inthe gas phase at low temperatures. Precursor molecules are broken downby energetic electrons present in the plasma to form free radicalspecies. These free radical species react at the substrate surface andlead to polymeric thin film growth. Due to the non-specificity of thereaction processes in both the gas phase and the substrate, theresulting polymer films are typically highly cross-linked and amorphousin nature. For additional information regarding plasma depositedpolymers, see, for example, H. Yasuda, “Plasma Polymerization,” AcademicPress Inc., New York (1985); R.d' Agostino (Ed), “Plasma Deposition,Treatment & Etching of Polymers,” Academic Press, New York (1990); andH. Biederman and Y. Osada, “Plasma Polymerization Processes,” Elsever,N.Y. (1992).

Typically, plasma deposited polymer layers described herein have anorganic nature due to the presence of hydrocarbon and carbonaceousfunctional groups such as CH₃, CH₂, CH, Si—C, Si—CH₃, Al—C, Si—O—CH₃,etc. The plasma deposited polymer layers are substantiallysub-stoichiometric in their inorganic component and substantiallycarbon-rich. In films containing silicon, for example, the oxygen tosilicon ratio is typically below 1.8 (silicon dioxide has a ratio of2.0), more typically below 1.5 for DLG, and the carbon content is atleast about 10%. In some embodiments, the carbon content is at leastabout 20% or 25%.

Amorphous diamond-like films formed via ion enhanced plasma chemicalvapor deposition (PECVD) utilizing silicone oil and an optional silanesource to form the plasma as described, for example, in U.S. Pat. App.Pub. No. 2008-0196664 (David et al.), can also be useful in barrierfilms. The terms “silicone”, “silicone oil”, or “siloxanes” are usedinterchangeably and refer to oligomeric and higher molecular weightmolecules having a structural unit R₂SiO in which R is independentlyselected from hydrogen, (C₁-C₈)alkyl, (C₅-C₁₈)aryl, (C₆-C₂₆)arylalkyl,or (C₆-C₂₆)alkylaryl. These can also be referred to aspolyorganosiloxanes and include chains of alternating silicon and oxygenatoms (—O—Si—O—Si—O—) with the free valences of the silicon atoms joinedusually to R groups, but may also be joined (crosslinked) to oxygenatoms and silicon atoms of a second chain, forming an extended network(high MW). In some embodiments, a siloxane source such as vaporizedsilicone oil is introduced in quantities such that the resulting plasmaformed coatings are flexible and have high optical transmission. Anyadditional useful process gases, such as oxygen, nitrogen and/orammonia, for example, can be used with the siloxane and optional silaneto assist in maintaining the plasma and to modify the properties of theamorphous diamond-like film layers.

In some embodiments, combinations of two or more different plasmadeposited polymers can be used. For example, different plasma depositedpolymer layers formed by changing or pulsing the process gases that formthe plasma for depositing the polymer layer. In another example, a firstlayer of a first amorphous diamond-like film can be formed and then asecond layer of a second amorphous diamond-like film can be formed onthe first layer, where the first layer has a different composition thanthe second layer. In some embodiments, a first amorphous diamond-likefilm layer is formed from a silicone oil plasma and then a secondamorphous diamond-like film layer is formed from a silicone oil andsilane plasma. In other embodiments, two or more amorphous diamond-likefilms layers of alternating composition are formed to create theamorphous diamond-like film.

Plasma deposited polymers such as diamond-like glass and diamond-likecarbon can be any useful thickness. In some embodiments, the plasmadeposited polymer can have a thickness of at least 500 Angstroms, or atleast 1,000 Angstroms. In some embodiments, the plasma deposited polymercan have a thickness in a range from 1,000 to 50,000 Angstroms, from1,000 to 25,000 Angstroms, or from 1,000 to 10,000 Angstroms.

Other plasma deposition processes for preparing useful barrier films 120such as carbon-rich films, silicon-containing films, or combinationsthereof are disclosed, for example, in U.S. Pat. No. 6,348,237 (Kohleret al.). Carbon-rich films may contain at least 50 atom percent carbon,and typically about 70-95 atom percent carbon, 0.1-20 atom percentnitrogen, 0.1-15 atom percent oxygen, and 0.1-40 atom percent hydrogen.Such carbon-rich films can be classified as “amorphous”, “hydrogenatedamorphous”, “graphitic”, “i-carbon”, or “diamond-like”, depending ontheir physical and chemical properties. Silicon-containing films areusually polymeric and contain in random composition silicon, carbon,hydrogen, oxygen, and nitrogen.

Carbon-rich films and silicon-containing films can be formed by means ofplasma interaction with a vaporized organic material, which is normallya liquid at ambient temperature and pressure. The vaporized organicmaterial is typically capable of condensing in a vacuum of less thanabout 1 Torr (130 Pa). The vapors are directed toward the polymeric filmsubstrate in a vacuum (e.g., in a conventional vacuum chamber) at anegatively charged electrode as described above for plasma polymerdeposition. A plasma (for example, an argon plasma or a carbon-richplasma as described in U.S. Pat. No. 5,464,667 (Kohler et al.)) and atleast one vaporized organic material are allowed to interact duringformation of a film. The plasma is one that is capable of activating thevaporized organic material. The plasma and vaporized organic materialcan interact either on the surface of the substrate or before contactingthe surface of the substrate. Either way, the interaction of thevaporized organic material and the plasma provides a reactive form ofthe organic material (for example, loss of methyl group from silicone)to enable densification of the material upon formation of the film, as aresult of polymerization and/or crosslinking, for example.Significantly, the films are prepared without the need for solvents.

The formed films can be uniform multi-component films (for example, onelayer coatings produced from multiple starting materials), uniformone-component films, and/or multilayer films (for example, alternatinglayers of carbon-rich material and silicone materials). For example,using a carbon-rich plasma in one stream from a first source and avaporized high molecular weight organic liquid such as dimethylsiloxaneoil in another stream from a second source, a one-pass depositionprocedure may result in a multilayer construction of the film (e.g., alayer of a carbon-rich material, a layer of dimethylsiloxane that is atleast partially polymerized, and an intermediate or interfacial layer ofa carbon/dimethylsiloxane composite). Variations in system arrangementsresult in the controlled formation of uniform multi-component films orlayered films with gradual or abrupt changes in properties andcomposition as desired. Uniform coatings of one material can also beformed from a carrier gas plasma, such as argon, and a vaporized highmolecular weight organic liquid, such as dimethylsiloxane oil.

Other useful barrier films 120 comprise films having agraded-composition barrier coating such as those described in U.S. Pat.No. 7,015,640 (Schaepkens et al.). Films having a graded-compositionbarrier coating can be made by depositing reaction or recombinationproducts of reacting species onto polymeric film substrate 130. Varyingthe relative supply rates or changing the identities of the reactingspecies results in a coating that has a graded composition across itsthickness. Suitable coating compositions are organic, inorganic, orceramic materials. These materials are typically reaction orrecombination products of reacting plasma species and are deposited ontothe substrate surface. Organic coating materials typically comprisecarbon, hydrogen, oxygen, and optionally other minor elements, such assulfur, nitrogen, silicon, etc., depending on the types of reactants.Suitable reactants that result in organic compositions in the coatingare straight or branched alkanes, alkenes, alkynes, alcohols, aldehydes,ethers, alkylene oxides, aromatics, etc., having up to 15 carbon atoms.Inorganic and ceramic coating materials typically comprise oxide;nitride; carbide; boride; or combinations thereof of elements of GroupsIIA, IIIA, IVA, VA, VIA, VIIA, IB, and IIB; metals of Groups IIIB, IVB,and VB; and rare-earth metals. For example, silicon carbide can bedeposited onto a substrate by recombination of plasmas generated fromsilane (SiH₄) and an organic material, such as methane or xylene.Silicon oxycarbide can be deposited from plasmas generated from silane,methane, and oxygen or silane and propylene oxide. Silicon oxycarbidealso can be deposited from plasmas generated from organosiliconeprecursors, such as tetraethoxysilane (TEOS), hexamethyldisiloxane(HMDSO), hexamethyldisilazane (HMDSN), or octamethylcyclotetrasiloxane(D4). Silicon nitride can be deposited from plasmas generated fromsilane and ammonia. Aluminum oxycarbonitride can be deposited from aplasma generated from a mixture of aluminum tartrate and ammonia. Othercombinations of reactants may be chosen to obtain a desired coatingcomposition. The choice of the particular reactants is within the skillsof the artisans. A graded composition of the coating can be obtained bychanging the compositions of the reactants fed into the reactor chamberduring the deposition of reaction products to form the coating or byusing overlapping deposition zones, for example, in a web process. Thecoating may be formed by one of many deposition techniques, such asplasma-enhanced chemical-vapor deposition (PECVD), radio-frequencyplasma-enhanced chemical-vapor deposition (RFPECVD), expandingthermal-plasma chemical-vapor deposition (ETPCVD), sputtering includingreactive sputtering, electron-cyclotron-resonance plasma-enhancedchemical-vapor deposition (ECRPECVD), inductively coupledplasma-enhanced chemical-vapor deposition (ICPECVD), or combinationsthereof. Coating thickness is typically in the range from about 10 nm toabout 10000 nm, in some embodiments from about 10 nm to about 1000 nm,and in some embodiments from about 10 nm to about 200 nm. The barrierfilm can have an average transmission over the visible portion of thespectrum of at least about 75% (in some embodiments at least about 80,85, 90, 92, 95, 97, or 98%) measured along the normal axis. In someembodiments, the barrier film has an average transmission over a rangeof 400 nm to 1400 nm of at least about 75% (in some embodiments at leastabout 80, 85, 90, 92, 95, 97, or 98%).

Other suitable barrier films include thin and flexible glass laminatedon a polymer film, and glass deposited on a polymeric film.

Pressure Sensitive Adhesive

PSAs are well known to those of ordinary skill in the art to possessproperties including the following: (1) aggressive and permanent tack,(2) adherence with no more than finger pressure, (3) sufficient abilityto hold onto an adherend, and (4) sufficient cohesive strength to becleanly removable from the adherend. Materials that have been found tofunction well as PSAs are polymers designed and formulated to exhibitthe requisite viscoelastic properties resulting in a desired balance oftack, peel adhesion, and shear holding power.

One method useful for identifying pressure sensitive adhesives is theDahlquist criterion. This criterion defines a pressure sensitiveadhesive as an adhesive having a 1 second creep compliance of greaterthan 1×10⁻⁶ cm²/dyne as described in “Handbook of Pressure SensitiveAdhesive Technology”, Donatas Satas (Ed.), 2^(nd) Edition, p. 172, VanNostrand Reinhold, New York, N.Y., 1989, incorporated herein byreference. Alternatively, since modulus is, to a first approximation,the inverse of creep compliance, pressure sensitive adhesives may bedefined as adhesives having a storage modulus of less than about 1×10⁶dynes/cm².

PSAs useful for practicing the present disclosure typically do not flowand have sufficient barrier properties to provide slow or minimalinfiltration of oxygen and moisture through the adhesive bond line.Also, the PSAs disclosed herein are generally transmissive to visibleand infrared light such that they do not interfere with absorption ofvisible light, for example, by photovoltaic cells. The PSAs may have anaverage transmission over the visible portion of the spectrum of atleast about 75% (in some embodiments at least about 80, 85, 90, 92, 95,97, or 98%) measured along the normal axis. In some embodiments, the PSAhas an average transmission over a range of 400 nm to 1400 nm of atleast about 75% (in some embodiments at least about 80, 85, 90, 92, 95,97, or 98%). Exemplary PSAs include acrylates, silicones,polyisobutylenes, ureas, and combinations thereof. Some usefulcommercially available PSAs include UV curable PSAs such as thoseavailable from Adhesive Research, Inc., Glen Rock, Pa., under the tradedesignations “ARclear 90453” and “ARclear 90537” and acrylic opticallyclear PSAs available, for example, from 3M Company, St. Paul, Minn.,under the trade designations “OPTICALLY CLEAR LAMINATING ADHESIVE 8171”,“OPTICALLY CLEAR LAMINATING ADHESIVE 8172”, and “OPTICALLY CLEARLAMINATING ADHESIVE 8172P”.

In some embodiments, PSAs useful for practicing the present disclosurehave a modulus (tensile modulus) up to 50,000 psi (3.4×10⁸ Pa). Thetensile modulus can be measured, for example, by a tensile testinginstrument such as a testing system available from Instron, Norwood,Mass., under the trade designation “INSTRON 5900”. In some embodiments,the tensile modulus of the PSA is up to 40,000, 30,000, 20,000, or10,000 psi (2.8×10⁸ Pa, 2.1×10⁸ Pa, 1.4×10⁸ Pa, or 6.9×10⁸ Pa).

In some embodiments, PSAs useful for practicing the present disclosureis are acrylic PSAs. As used herein, the term “acrylic” or “acrylate”includes compounds having at least one of acrylic or methacrylic groups.Useful acrylic PSAs can be made, for example, by combining at least twodifferent monomers (first and second monomers). Exemplary suitable firstmonomers include 2-methylbutyl acrylate, 2-ethylhexyl acrylate, isooctylacrylate, lauryl acrylate, n-decyl acrylate, 4-methyl-2-pentyl acrylate,isoamyl acrylate, sec-butyl acrylate, and isononyl acrylate. Exemplarysuitable second monomers include a (meth)acrylic acid (e.g., acrylicacid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid), a(meth)acrylamide (e.g., acrylamide, methacrylamide, N-ethyl acrylamide,N-hydroxyethyl acrylamide, N-octyl acrylamide, N-t-butyl acrylamide,N,N-dimethyl acrylamide, N,N-diethyl acrylamide, andN-ethyl-N-dihydroxyethyl acrylamide), a (meth)acrylate (e.g.,2-hydroxyethyl acrylate or methacrylate, cyclohexyl acrylate, t-butylacrylate, or isobornyl acrylate), N-vinyl pyrrolidone, N-vinylcaprolactam, an alpha-olefin, a vinyl ether, an allyl ether, a styrenicmonomer, or a maleate.

Acrylic PSAs may also be made by including cross-linking agents in theformulation. Exemplary cross-linking agents include copolymerizablepolyfunctional ethylenically unsaturated monomers (e.g., 1,6-hexanedioldiacrylate, trimethylolpropane triacrylate, pentaerythritoltetraacrylate, and 1,2-ethylene glycol diacrylate); ethylenicallyunsaturated compounds which in the excited state are capable ofabstracting hydrogen (e.g., acrylated benzophenones such as described inU.S. Pat. No. 4,737,559 (Kellen et al.), p-acryloxy-benzophenone, whichis available from Sartomer Company, Exton, Pa., monomers described inU.S. Pat. No. 5,073,611 (Rehmer et al.) includingp-N-(methacryloyl-4-oxapentamethylene)-carbamoyloxybenzophenone,N-(benzoyl-p-phenylene)-N′-(methacryloxymethylene)-carbodiimide, andp-acryloxy-benzophenone); nonionic crosslinking agents which areessentially free of olefinic unsaturation and is capable of reactingwith carboxylic acid groups, for example, in the second monomerdescribed above (e.g., 1,4-bis(ethyleneiminocarbonylamino)benzene;4,4-bis(ethyleneiminocarbonylamino)diphenylmethane;1,8-bis(ethyleneiminocarbonylamino)octane; 1,4-tolylene diisocyanate;1,6-hexamethylene diisocyanate, N,N′-bis-1,2-propyleneisophthalamide,diepoxides, dianhydrides, bis(amides), and bis(imides)); and nonioniccrosslinking agents which are essentially free of olefinic unsaturation,are noncopolymerizable with the first and second monomers, and, in theexcited state, are capable of abstracting hydrogen (e.g.,2,4-bis(trichloromethyl)-6-(4-methoxy)phenyl)-s-triazine;2,4-bis(trichloromethyl)-6-(3,4-dimethoxy)phenyl)-s-triazine;2,4-bis(trichloromethyl)-6-(3,4,5-trimethoxy)phenyl)-s-triazine;2,4-bis(trichloromethyl)-6-(2,4-dimethoxy)phenyl)-s-triazine;2,4-bis(trichloromethyl)-6-(3-methoxy)phenyl)-s-triazine as described inU.S. Pat. No. 4,330,590 (Vesley);2,4-bis(trichloromethyl)-6-naphthenyl-s-triazine and2,4-bis(trichloromethyl)-6-(4-methoxy)naphthenyl-s-triazine as describedin U.S. Pat. No. 4,329,384 (Vesley)).

Typically, the first monomer is used in an amount of 80-100 parts byweight (pbw) based on a total weight of 100 parts of copolymer, and thesecond monomer is used in an amount of 0-20 pbw based on a total weightof 100 parts of copolymer. The crosslinking agent can be used in anamount of 0.005 to 2 weight percent based on the combined weight of themonomers, for example from about 0.01 to about 0.5 percent by weight orfrom about 0.05 to 0.15 percent by weight.

The acrylic PSAs useful for practicing the present disclosure can beprepared, for example, by a solvent free, bulk, free-radicalpolymerization process (e.g., using heat, electron-beam radiation, orultraviolet radiation). Such polymerizations are typically facilitatedby a polymerization initiator (e.g., a photoinitiator or a thermalinitiator). Examplary suitable photoinitiators include benzoin etherssuch as benzoin methyl ether and benzoin isopropyl ether, substitutedbenzoin ethers such as anisoin methyl ether, substituted acetophenonessuch as 2,2-dimethoxy-2-phenylacetophenone, and substituted alpha-ketolssuch as 2-methyl-2-hydroxypropiophenone. Examples of commerciallyavailable photoinitiators include IRGACURE 651 and DAROCUR 1173, bothavailable from Ciba-Geigy Corp., Hawthorne, N.Y., and LUCERIN TPO fromBASF, Parsippany, N.J. Examples of suitable thermal initiators include,but are not limited to, peroxides such as dibenzoyl peroxide, dilaurylperoxide, methyl ethyl ketone peroxide, cumene hydroperoxide,dicyclohexyl peroxydicarbonate, as well as2,2-azo-bis(isobutryonitrile), and t-butyl perbenzoate. Examples ofcommercially available thermal initiators include VAZO 64, availablefrom ACROS Organics, Pittsburgh, Pa., and LUCIDOL 70, available from ElfAtochem North America, Philadelphia, Pa. The polymerization initiator isused in an amount effective to facilitate polymerization of the monomers(e.g., 0.1 part to about 5.0 parts or 0.2 part to about 1.0 part byweight, based on 100 parts of the total monomer content).

If a photocrosslinking agent is used, the coated adhesive can be exposedto ultraviolet radiation having a wavelength of about 250 nm to about400 nm. The radiant energy in this range of wavelength required tocrosslink the adhesive is about 100 millijoules/cm² to about 1,500millijoules/cm², or more specifically, about 200 millijoules/cm² toabout 800 millijoules/cm².

A useful solvent-free polymerization method is disclosed in U.S. Pat.No. 4,379,201 (Heilmann et al.). Initially, a mixture of first andsecond monomers can be polymerized with a portion of a photoinitiator byexposing the mixture to UV radiation in an inert environment for a timesufficient to form a coatable base syrup, and subsequently adding acrosslinking agent and the remainder of the photoinitiator. This finalsyrup containing a crosslinking agent (e.g., which may have a Brookfieldviscosity of about 100 centipoise to about 6000 centipoise at 23 C., asmeasured with a No. 4 LTV spindle, at 60 revolutions per minute) canthen be coated onto the second polymeric film substrate. Once the syrupis coated onto the second polymeric film substrate, furtherpolymerization and crosslinking can be carried out in an inertenvironment (e.g., nitrogen, carbon dioxide, helium, and argon, whichexclude oxygen). A sufficiently inert atmosphere can be achieved bycovering a layer of the photoactive syrup with a polymeric film, such assilicone-treated PET film, that is transparent to UV radiation or e-beamand irradiating through the film in air.

In some embodiments, PSAs useful for practicing the present disclosurecomprise polyisobutylene. The polyisobutylene may have a polyisobutyleneskeleton in the main or a side chain. Useful polyisobutylenes can beprepared, for example, by polymerizing isobutylene alone or incombination with n-butene, isoprene, or butadiene in the presence of aLewis acid catalyst (for example, aluminum chloride or borontrifluoride).

Useful polyisobutylene materials are commercially available from severalmanufacturers. Homopolymers are commercially available, for example,under the trade designations “OPPANOL” and “GLISSOPAL” (e.g., OPPANOLB15, B30, B50, B100, B150, and B200 and GLISSOPAL 1000, 1300, and 2300)from BASF Corp. (Florham Park, N.J.); “SDG”, “JHY”, and “EFROLEN” fromUnited Chemical Products (UCP) of St. Petersburg, Russia.Polyisobutylene copolymers can be prepared by polymerizing isobutylenein the presence of a small amount (e.g., up to 30, 25, 20, 15, 10, or 5weight percent) of another monomer such as, for example, styrene,isoprene, butene, or butadiene. Exemplary suitable isobutylene/isoprenecopolymers are commercially available under the trade designations“EXXON BUTYL” (e.g., EXXON BUTYL 065, 068, and 268) from Exxon MobilCorp., Irving, Tex.; “BK-1675N” from UCP and “LANXESS” (e.g., LANXESSBUTYL 301, LANXESS BUTYL 101-3, and LANXESS BUTYL 402) from Sarnia,Ontario, Canada. Exemplary suitable isobutylene/styrene block copolymersare commercially available under the trade designation “SIBSTAR” fromKaneka (Osaka, Japan). Other exemplary suitable polyisobutylene resinsare commercially available, for example, from Exxon Chemical Co. underthe trade designation “VISTANEX”, from Goodrich Corp., Charlotte, N.C.,under the trade designation “HYCAR”, and from Japan Butyl Co., Ltd.,Kanto, Japan, under the trade designation “JSR BUTYL”.

A polyisobutylene useful for practicing the present disclosure may havea wide variety of molecular weights and a wide variety of viscosities.Polyisobutylenes of many different molecular weights and viscosities arecommercially available.

In some embodiments of PSAs comprising polyisobutylene, the PSA furthercomprises a hydrogenated hydrocarbon tackifier (in some embodiments, apoly(cyclic olefin)). In some of these embodiments, about 5 to 90percent by weight the hydrogenated hydrocarbon tackifier (in someembodiments, the poly(cyclic olefin)) is blended with about 10 to 95percent by weight polyisobutylene, based on the total weight of the PSAcomposition. Useful polyisobutylene PSAs include adhesive compositionscomprising a hydrogenated poly(cyclic olefin) and a polyisobutyleneresin such as those disclosed in Int. Pat. App. Pub. No. WO 2007/087281(Fujita et al.).

The “hydrogenated” hydrocarbon tackifier component may include apartially hydrogenated resin (e.g., having any hydrogenation ratio), acompletely hydrogenated resin, or a combination thereof. In someembodiments, the hydrogenated hydrocarbon tackifier is completelyhydrogenated, which may lower the moisture permeability of the PSA andimprove the compatibility with the polyisobutylene resin. Thehydrogenated hydrocarbon tackifiers are often hydrogenatedcycloaliphatic resins, hydrogenated aromatic resins, or combinationsthereof. For example, some tackifying resins are hydrogenated C9-typepetroleum resins obtained by copolymerizing a C9 fraction produced bythermal decomposition of petroleum naphtha, hydrogenated C5-typepetroleum resins obtained by copolymerizing a C5 fraction produced bythermal decomposition of petroleum naphtha, or hydrogenated C5/C9-typepetroleum resins obtained by polymerizing a combination of a C5 fractionand C9 fraction produced by thermal decomposition of petroleum naphtha.The C9 fraction can include, for example, indene, vinyl-toluene,alpha-methylstyrene, beta-methylstyrene, or a combination thereof. TheC5 fraction can include, for example, pentane, isoprene, piperidine,1,3-pentadiene, or a combination thereof. In some embodiments, thehydrogenated hydrocarbon tackifier is a hydrogenated poly(cyclicolefin)polymer. In some embodiments, the hydrogenated poly(cyclicolefin) is a hydrogenated poly(dicyclopentadiene), which may provideadvantages to the PSA (e.g., low moisture permeability andtransparency). The tackifying resins are typically amorphous and have aweight average molecular weight no greater than 5000 grams/mole.

Some suitable hydrogenated hydrocarbon tackifiers are commerciallyavailable under the trade designations “ARKON” (e.g., ARKON P or ARKONM) from Arakawa Chemical Industries Co., Ltd. (Osaka, Japan); “ESCOREZ”from Exxon Chemical; “REGALREZ” (e.g., REGALREZ 1085, 1094, 1126, 1139,3102, and 6108) from Eastman (Kingsport, Tenn.); “WINGTACK” (e.g.,WINGTACK 95 and RWT-7850) resins from Cray Valley (Exton, Pa.);“PICCOTAC” (e.g., PICCOTAC 6095-E, 8090-E, 8095, 8595, 9095, and 9105)from Eastman; “CLEARON”, in grades P, M and K, from Yasuhara Chemical,Hiroshima, Japan; “FORAL AX” and “FORAL 105” from Hercules Inc.,Wilmington, Del.; “PENCEL A”, “ESTERGUM H”, “SUPER ESTER A”, and“PINECRYSTAL” from Arakawa Chemical Industries Co., Ltd., Osaka, Japan;from Arakawa Chemical Industries Co., Ltd.); “EASTOTAC H” from Eastman;and “IMARV” from Idemitsu Petrochemical Co., Tokyo, Japan.

Optionally PSAs useful for practicing the present disclosure (includingany of the embodiments of PSAs described above) comprise at least one ofa uv absorber (UVA), a hindered amine light stabilizer, or anantioxidant. Examples of useful UVAs include those described above inconjunction with multilayer film substrates (for example, thoseavailable from Ciba Specialty Chemicals Corporation under the tradedesignations “TINUVIN 328”, “TINUVIN 326”, “TINUVIN 783”, “TINUVIN 770”,“TINUVIN 479”, “TINUVIN 928”, and “TINUVIN 1577”). UVAs, when used, canbe present in an amount from about 0.01 to 3 percent by weight based onthe total weight of the pressure sensitive adhesive composition.Examples of useful antioxidants include hindered phenol-based compoundsand phosphoric acid ester-based compounds and those described above inconjunction with multilayer film substrates (e.g., those available fromCiba Specialty Chemicals Corporation under the trade designations“IRGANOX 1010”, “IRGANOX 1076”, and “IRGAFOS 126” and butylatedhydroxytoluene (BHT)). Antioxidants, when used, can be present in anamount from about 0.01 to 2 percent by weight based on the total weightof the pressure sensitive adhesive composition. Examples of usefulstabilizers include phenol-based stabilizers, hindered amine-basedstabilizers (e.g., including those described above in conjunction withmultilayer film substrates and those available from BASF under the tradedesignation “CHIMASSORB” such as “CHIMASSORB 2020”), imidazole-basedstabilizers, dithiocarbamate-based stabilizers, phosphorus-basedstabilizers, and sulfur ester-based stabilizers. Such compounds, whenused, can be present in an amount from about 0.01 to 3 percent by weightbased on the total weight of the pressure sensitive adhesivecomposition.

In some embodiments, the PSA layer disclosed herein is at least 0.005 mm(in some embodiments, at least 0.01, 0.02, 0.03, 0.04, or 0.05 mm) inthickness. In some embodiments, the PSA layer has a thickness up toabout 0.2 mm (in some embodiments, up to 0.15, 0.1, or 0.075 mm) inthickness. For example, the thickness of the PSA layer may be in a rangefrom 0.005 mm to 0.2 mm, 0.005 mm to 0.1 mm, or 0.01 to 0.1 mm.

Once the PSA layer has been applied to the second polymeric filmsubstrate, the exposed major surface may be temporarily protected with arelease liner before being applied to a barrier film disclosed herein.Examples of useful release liners include craft paper coated with, forexample, silicones; polypropylene film; fluoropolymer film such as thoseavailable from E.I. du Pont de Nemours and Co. under the tradedesignation “TEFLON”; and polyester and other polymer films coated with,for example, silicones or fluorocarbons.

Without wanting to be bound be theory, it is believed that the PSA layerin the barrier assembly according to the present disclosure serves toprotect the barrier assembly from thermal stresses that may be caused bya high CTE second polymeric film substrate (e.g., a fluoropolymer).Furthermore, even in embodiments wherein the CTE mismatch between thefirst and second polymeric film substrates is relatively low (e.g., lessthan 40 ppm/K) the PSA layer serves as a convenient means for attachingthe second polymeric film substrate to the barrier film deposited on thefirst polymeric film substrate (e.g., having a CTE of up to 50 ppm/K).When the PSA layer contains at least one of UVA, HALS, or anti-oxidants,it can further provide protection to the barrier film from degradationby UV light.

Other Optional Features

Optionally, assemblies according to the present disclosure can containdesiccant. In some embodiments, assemblies according to the presentdisclosure are essentially free of desiccant. “Essentially free ofdesiccant” means that desiccant may be present but in an amount that isinsufficient to effectively dry a photovoltaic module. Assemblies thatare essentially free of desiccant include those in which no desiccant isincorporated into the assembly.

Various functional layers or coatings can optionally be added to theassemblies disclosed herein to alter or improve their physical orchemical properties. Exemplary useful layers or coatings include visibleand infrared light-transmissive conductive layers or electrodes (e.g.,of indium tin oxide); antistatic coatings or films; flame retardants;abrasion resistant or hardcoat materials; optical coatings; anti-foggingmaterials; anti-reflection coatings; anti-smudging coatings; polarizingcoatings; anti-fouling materials; prismatic films; additional adhesives(e.g., pressure sensitive adhesives or hot melt adhesives); primers topromote adhesion to adjacent layers; additional UV protective layers;and low adhesion backsize materials for use when the barrier assembly isto be used in adhesive roll form. These components can be incorporated,for example, into the barrier film or can be applied to the surface ofthe polymeric film substrate.

Other optional features that can be incorporated into the assemblydisclosed herein include graphics and spacer structures. For example,the assembly disclosed herein could be treated with inks or otherprinted indicia such as those used to display product identification,orientation or alignment information, advertising or brand information,decoration, or other information. The inks or printed indicia can beprovided using techniques known in the art (e.g., screen printing,inkjet printing, thermal transfer printing, letterpress printing, offsetprinting, flexographic printing, stipple printing, and laser printing).Spacer structures could be included, for example, in the adhesive, tomaintain specific bond line thickness.

Assemblies according to the present disclosure can conveniently beassembled using a variety of techniques. For example, the pressuresensitive adhesive layer may be a transfer PSA on a release liner orbetween two release liners. The transfer adhesive can be used tolaminate a second polymeric film substrate to a barrier film depositedon a first polymeric film substrate after removal of the releaseliner(s). In another example, a PSA can be coated onto the secondpolymeric film substrate and/or onto the barrier film deposited on thefirst polymeric film substrate before laminating the first and secondpolymeric film substrates together. In a further example, a solvent-freeadhesive formulation, for example, can be coated between the secondpolymeric film substrate and the barrier film deposited on the firstpolymeric film substrate. Subsequently, the formulation can be cured byheat or radiation as described above to provide an assembly according tothe present disclosure.

Assemblies according to the present disclosure are useful, for example,for encapsulating solar devices. In some embodiments, the assembly isdisposed on, above, or around a photovoltaic cell. Accordingly, thepresent disclosure provides a method comprising applying an assemblydisclosed herein to the front surface of a photovoltaic cell. Suitablesolar cells include those that have been developed with a variety ofmaterials each having a unique absorption spectra that converts solarenergy into electricity. Each type of semiconductor material will have acharacteristic band gap energy which causes it to absorb light mostefficiently at certain wavelengths of light, or more precisely, toabsorb electromagnetic radiation over a portion of the solar spectrum.Examples of materials used to make solar cells and their solar lightabsorption band-edge wavelengths include: crystalline silicon singlejunction (about 400 nm to about 1150 nm), amorphous silicon singlejunction (about 300 nm to about 720 nm), ribbon silicon (about 350 nm toabout 1150 nm), CIS (Copper Indium Selenide) (about 400 nm to about 1300nm), CIGS (Copper Indium Gallium di-Selenide) (about 350 nm to about1100 nm), CdTe (about 400 nm to about 895 nm), GaAs multi junction(about 350 nm to about 1750 nm). The shorter wavelength left absorptionband edge of these semiconductor materials is typically between 300 nmand 400 nm. One skilled in the art understands that new materials arebeing developed for more efficient solar cells having their own uniquelonger wavelength absorption band-edge and the multilayer reflectivefilm would have a corresponding reflective band-edge. In someembodiments, the assembly disclosed herein is disposed on, above, oraround a CIGS cell. In some embodiments of barrier assemblies accordingto the present disclosure, the solar device (e.g., the photovoltaiccell) to which the assembly is applied comprises a flexible filmsubstrate.

Barrier assemblies may also be useful, for example, for displays such aselectrophoretic, electrochromic, and OLED displays.

Selected Embodiments of the Disclosure

In a first embodiment, the present disclosure provides an assemblycomprising:

a barrier film interposed between:

-   -   a first polymeric film substrate having a first coefficient of        thermal expansion, and    -   a first major surface of a pressure sensitive adhesive layer,        wherein the pressure sensitive adhesive layer has a second major        surface opposite the first major surface that is disposed on a        second polymeric film substrate having a second coefficient of        thermal expansion,        wherein the assembly is transmissive to visible and infrared        light, and wherein the second coefficient of thermal expansion        is at least 40 parts per million per Kelvin higher than the        first coefficient of thermal expansion.

In a second embodiment, the present disclosure provides an assemblyaccording to the first embodiment, wherein second coefficient of thermalexpansion is at least 80 parts per million per Kelvin higher than thefirst coefficient of thermal expansion.

In a third embodiment, the present disclosure provides an assemblyaccording to the first embodiment, wherein second coefficient of thermalexpansion is at least 100 parts per million per Kelvin higher than thefirst coefficient of thermal expansion.

In a fourth embodiment, the present disclosure provides an assemblycomprising:

a barrier film interposed between:

-   -   a first polymeric film substrate having a coefficient of thermal        expansion of up to 50 parts per million per Kelvin, and    -   a first major surface of a pressure sensitive adhesive layer,        wherein the pressure sensitive adhesive layer has a second major        surface opposite the first major surface that is disposed on a        second polymeric film substrate,        wherein the assembly is transmissive to visible and infrared        light, and wherein the second polymeric film substrate is        resistant to degradation by ultraviolet light.

In a fifth embodiment, the present disclosure provides an assemblyaccording to the fourth embodiment, wherein the coefficient of thermalexpansion of the first polymeric film substrate is up to 30 parts permillion per Kelvin.

In a sixth embodiment, the present disclosure provides an assemblyaccording to the fourth or fifth embodiment, wherein the secondpolymeric film substrate is a multilayer optical film.

In a seventh embodiment, the present disclosure provides an assemblyaccording to any of the fourth to sixth embodiments, the secondpolymeric film substrate at least one of reflects or absorbs at least 50percent of incident ultraviolet light over at least a 30 nanometer rangein a wavelength range from at least 300 nanometers to 400 nanometers.

In an eighth embodiment, the present disclosure provides an assemblyaccording to any one of the first to seventh embodiments, wherein aratio of the thickness of the first polymeric film to the secondpolymeric film is at least 5:2.

In a ninth embodiment, the present disclosure provides an assemblyaccording to any one of the first to eighth embodiments, wherein theassembly has a curl of up to 7 m⁻¹.

In a tenth embodiment, the present disclosure provides an assemblyaccording to any one of the first to ninth embodiments, wherein thefirst polymeric film substrate has a thickness of at least 0.5millimeters.

In an eleventh embodiment, the present disclosure provides an assemblyaccording to any one of the first to tenth embodiments, wherein thepressure sensitive adhesive layer has a tensile modulus of up to 3.4×10⁸Pascals.

In a twelfth embodiment, the present disclosure provides an assemblyaccording to any one of the first to eleventh embodiments, wherein thepressure sensitive adhesive is at least one of an acrylate, a silicone,a polyisobutylene, or a urea pressure sensitive adhesive. In some ofthese embodiments, the pressure sensitive adhesive is at least one of anacrylate or polyisobutylene pressure sensitive adhesive.

In a thirteenth embodiment, the present disclosure provides an assemblyaccording to any one of the first to twelfth embodiments, wherein thepressure sensitive adhesive further comprises at least one of a uvstabilizer, a hindered amine light stabilizer, and antioxidant, or athermal stabilizer.

In a fourteenth embodiment, the present disclosure provides an assemblyaccording to any one of the first to thirteenth embodiments, wherein thepressure sensitive adhesive layer has a thickness of at least 0.05millimeter.

In a fifteenth embodiment, the present disclosure provides an assemblyaccording to any one of the first to fourteenth embodiments, wherein thesecond polymeric film substrate comprises a fluoropolymer.

In a sixteenth embodiment, the present disclosure provides an assemblyaccording to the fifteenth embodiment, wherein the second polymeric filmsubstrate comprises at least one of an ethylene-tetrafluoroethylenecopolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, atetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer,or polyvinylidene fluoride.

In a seventeenth embodiment, the present disclosure provides an assemblyaccording to any one of the first to sixteenth embodiments, wherein thebarrier film comprises at least first and second polymer layersseparated by an inorganic barrier layer.

In an eighteenth embodiment, the present disclosure provides an assemblyaccording to the seventeenth embodiment, wherein the inorganic barrierlayer is an oxide layer that shares a siloxane bond with at least one ofthe first or second polymer layers.

In a nineteenth embodiment, the present disclosure provides an assemblyaccording to the seventeenth embodiment, wherein at least one of thefirst or second polymer layers comprises co-deposited silane andacrylate monomers.

In a twentieth embodiment, the present disclosure provides an assemblyaccording to any one of the first to nineteenth embodiments, wherein thebarrier film has at least one of an oxygen transmission rate less than0.005 g/m²/day at 23° C. and 90% relative humidity or a water vaportransmission rate less than 0.005 g/m²/day at 50° C. and 100% relativehumidity.

In a twenty-first embodiment, the present disclosure provides anassembly according to any one of the first to twentieth embodiments,wherein the assembly is disposed on, above, or around a photovoltaiccell.

In a twenty-second embodiment, the present disclosure provides anassembly according to the twenty-first embodiment, wherein thephotovoltaic cell is a CIGS cell.

In a twenty-third embodiment, the present disclosure provides anassembly according to any one of the first to twenty-second embodiments,wherein the first polymeric film substrate comprises at least one ofpolyethylene terephthalate, polyethylene naphthalate,polyetheretherketone, polyaryletherketone, polyarylate, polyetherimide,polyarylsulfone, polyethersulfone, polyamideimide, or polyimide, any ofwhich may optionally be heat-stabilized.

In a twenty-fourth embodiment, the present disclosure provides anassembly according to any one of the first to twenty-third embodiments,wherein the first polymeric film substrate has a tensile modulus of atleast 2×10⁹ Pascals.

In a twenty-fifth embodiment, the present disclosure provides anassembly according to any one of the first to twenty-fourth embodiments,wherein a ratio of a tensile modulus of the first polymeric filmsubstrate to a tensile modulus of the second polymeric film substrate isat least 2 to 1.

In a twenty-sixth embodiment, the present disclosure provides anassembly according to the twenty-third embodiment, wherein the firstpolymeric film layer comprises polyethylene terephthalate.

In a twenty-seventh embodiment, the present disclosure provides anassembly according to any one of the first to twenty-sixth embodiments,wherein the second polymeric film substrate comprisesethylene-tetrafluoroethylene copolymer.

In a twenty-eighth embodiment, the present disclosure provides anassembly according to any one of the first to twenty-sixth embodiments,wherein the second polymeric film substrate comprises polyvinylidenefluoride.

In a twenty-ninth embodiment, the present disclosure provides anassembly according to any one of the first to twenty-sixth embodiments,wherein the second polymeric film substrate comprises polyvinylidenefluoride and polymethyl methacrylate.

Embodiments and advantages of this disclosure are further illustrated bythe following non-limiting examples, but the particular materials andamounts thereof recited in these examples, as well as other conditionsand details, should not be construed to unduly limit this disclosure.

EXAMPLES Materials

90% Si/10% Al targets were obtained from Academy Precision MaterialsInc., Albuquerque, N. Mex.

99.999% Si targets were obtained from Academy Precision Materials Inc.,Albuquerque, N. Mex.

8172P: “3M OPTICALLY CLEAR ADHESIVE 8172P” commercially available from3M Company, St. Paul, Minn.

ETFE: ethylene-tetrafluoroethylene film with surface treatment(C-treated) available from St. Gobain Performance Plastics, Wayne, N.J.under the trade name “NORTON® ETFE”.

ADCO PVA: an encapsulant available from ADCO Products, Inc. MichiganCenter, Mich. under the trade name “HELIOBOND PVA 100 EVA”.

Etimex 496.10: an encapsulant available from Etimex, Dietenheim, Germanyunder the trade name “VISTASOLAR® 496.10”.

“JURASOL® TL”: an encapsulant available from jura-plast GmbH,Reichenschwand Germany.

Madico TAPE: back-sheet film commercially available under the tradedesignation “TAPE” from Madico, Woburn, Mass.

N-n-butyl-aza-2,2-dimethoxysilacyclopentane was obtained from Gelest,Inc., Morrisville, Pa.

PSA-A: Pressure Sensitive Adhesive (PSA) prepared according to Example 4from PCT Publication WO 2007087281 (Fujita et al.) except that therubber/tackifier ratio was 75/25 instead of 60/40 and the rubber used 2parts B80 to 1 part B50.

PVDF Film: Polyvinylidene fluoride film obtained under the tradedesignation (ROWLAR Film FEO-MG-000 C) from Rowland Technologies,Wallingford, Conn. Examples use 0.05 mm (0.002 inch) thick film.

“SR-8335”: tricyclodecane dimethanol diacrylate available from SartomerUSA, LLC, Exton, Pa.

“SCOTCHCAL 3640 GPS”: a weatherable overlaminate adhesive film availablefrom 3M Company, St. Paul, Minn.

Stainless-steel feeler gage: roll of stainless steel gage commerciallyavailable under the trade designation “Starrett 666-1 feeler gage”.Examples used a 25 micron (0.001 inch) thick gage.

Tinned copper foil: available from Ulbrich, North Haven Conn. Examplesuse 0.035 mm thick by 12 mm wide by 128 mm long strips.

UV-PET: UV PolyEthylene Terephthalate film available under the name“XST-6578” from DuPont Teijin Films, Hopewell Va.

T-Peel Test Method

Films having a barrier coating were cut to 20 cm (8 inch)×30.5 cm (12inch) rectangular sections. These sections were then placed into alaminate construction containing a bottom back-sheet (Madico TAPE), alayer of encapsulant adjacent to the back-sheet, and the barrier film ontop of the encapsulant layer with the barrier coating oriented towardsthe encapsulant. The construction was laminated at 150° C. for 12minutes and 10⁵ Pa (1 atm) of pressure. Two pieces of plastic materialabout 25 mm wide by 20 cm long were placed between the barrier film andthe adhesive layer along both 20 cm long edges to form unbonded edges.The resulting laminate was then cut into 25 mm wide×152 mm long stripssuch that one end contained the 25 mm unbonded ends that were to beplaced in the clamping grips of the test machine. The two unbonded endsof film were placed in a tension testing machine according to ASTMD1876-08 “Standard Test Method for Peel Resistance of Adhesives (T-PeelTest)”. A grip distance of 12.7 mm was used and a peel speed of 254mm/min (10 inches/min) was used. T-Peel testing was completed accordingto ASTM D1876-08 except where otherwise stated. The average peel forcewas measured for three samples and averaged to produce the results

Curl Test Method

Curl measurements were conducted as described in “Measurement of WebCurl” by Ronald P. Swanson presented in the 2006 AWEB conferenceproceedings (Association of Industrial Metallizers, Coaters andLaminators, Applied Web Handling Conference Proceedings, 2006). The curlgauge was constructed by inserting a pair of pins about 3 cm long into avertically positioned aluminum plate. The pins were positionedhorizontally and spaced about 56 mm apart. The curl gauge was calibratedusing cylinders with known diameters. The curvature of a cylinder is thereciprocal of the radius of the cylinder. Each cylinder was placed ontop of the pins so that the cylinder was supported by the pins. Theouter diameter of each the cylinder was traced on the aluminum plate toprovide lines of constant known curvature. Samples about 10 cm in lengthand 1.3 cm in width were tested by placing the sample strips on top ofthe pins and determining the curvature by observing how the ends of thesample aligns with the lines of constant curvature drawn on the aluminumpanel. The curl was determined as the curvature of the sample strips.The curl gauge was able to accurately measure the amount of curl to aresolution of 0.25 m⁻¹.

A separate pair of horizontally positioned pins that were about 3 cmlong was inserted into the aluminum panel with a spacing of about 84 mm.These pins were used to measure the curvature of samples having a lengthof 15 cm in the same way that the first pair of pins was used to measurethe curvature of samples having a 10 cm length.

Preparative Example 1 ETFE(0.13 mm)/Barrier Layer

An ethylene-tetrafluoroethylene (ETFE) support film was treated with anitrogen plasma and then covered respectively with barrier layers ofacrylate, silicon aluminum oxide (SiAlOx), silicon-sub-oxide (SiOx), asecond acrylate, and a second SiAlOx layer. Examples of barrierassemblies were made on a vacuum coater similar to the coater describedin U.S. Pat. Nos. 5,440,446 (Shaw et al.) and 7,018,713 (Padiyath, etal.). The individual layers were formed as follows:

(Layer 1—smoothing polymeric layer) A 300 meter long roll of 0.127 mmthick×356 mm wide surface treated (C-treated) ETFE film was loaded intoa roll-to-roll vacuum processing chamber with the C-treated side facing“up” and the non-C-treated side in contact with the coating drum. Thechamber was pumped down to a pressure of 2×10⁻⁵ Torr. The web speed wasset at 3.7 meters/min while maintaining the backside of the film incontact with a coating drum chilled to −10° C. With the backside of theETFE film in contact with the drum, the front side film surface wastreated with a nitrogen plasma formed by flowing 100 standard cubiccentimeters per minute (sccm) of nitrogen over a magnetically enhancedcathode in the presence of 0.05 kW of power (obtained from ENI Products,Rochester, N.Y., under the trade designation “ENI DCG-100”) Immediatelyafter the nitrogen plasma treatment, the film was coated withtricyclodecane dimethanol di-acrylate “SR-833S”. The di-acrylate wasdegassed to a pressure of 20 mTorr (2.7 Pa) prior to coating, and pumpedat a flow rate of 1.0 mL/min through an ultrasonic atomizer (Sono-TekCorporation, Milton, N.Y.) operated at a frequency of 60 kHz into aheated vaporization chamber maintained at 260° C. The resulting monomervapor stream condensed onto the film surface and was polymerized afterelectron beam exposure using a multi-filament electron gun operated at9.0 kV and 3.0 mA to form a 725 nm acrylate layer.

(Layer 2—inorganic layer) Immediately after the acrylate deposition andwith the film still in contact with the drum, a SiAlOx layer wassputter-deposited atop a 60 meter length of the plasma treated andacrylate-coated ETFE film surface. Two alternating current (AC) powersupplies (obtained from Advanced Energy, Fort Collins, C.O., under thetrade designation “PE-II”) were used to control two pairs of cathodes,with each cathode housing two targets. Each cathode pair contained two90% Si/10% Al targets During sputter deposition, the voltage signal fromeach power supply was used as an input for aproportional-integral-differential control loop to maintain a proscribedoxygen flow to each cathode pair. The AC power supplies sputtered the90% Si/10% Al targets using 3500 watts of power each, and a total gasmixture containing 950 sccm argon and 70 sccm oxygen at a sputterpressure of 3.4 millitorr (0.45 Pa). This provided a 30 nm thick SiAlOxlayer deposited atop the acrylate coating.

(Layer 3—inorganic layer) Immediately after the SiAlOx deposition andwith the film still in contact with the drum, a sub-oxide of silicon(SiOx, where x<2) tie-layer was sputter deposited atop the same 60 meterlength of the SiAlOx and acrylate coated ETFE film surface using a99.999% Si target. The SiOx was sputtered using 1000 watts of pulsed-DCpower (obtained from Advanced Energy) at a frequency of 90 kHz, areverse time of 4.4 microseconds, and a reverse voltage set to 10% ofthe DC voltage using a gas mixture containing 10 sccm of oxygen at asputter pressure of 2 millitorr (0.27 Pa) to provide a SiOx layer 5 nmthick atop SiAlOx layer.

(Layer 4—protective polymeric layer) Immediately after the SiOx layerdeposition and with the film still in contact with the drum, a secondacrylate was coated and cross linked on the same 60 meter web lengthusing the same conditions as for the first acrylate layer but with thefollowing exceptions: electron beam cross linking was carried out usinga multi-filament cure gun operated at 9 kV and 0.41 mA. This provided a725 nm acrylate layer.

(Layer 5—inorganic layer) In a separate pass through the roll-to-rollvacuum processing chamber and with the web at 3.7 meters/minute, asecond SiAlOx was sputter deposited atop the same 60 meter web lengthusing the same conditions as above. This provided a 30 nm thick SiAlOxlayer deposited atop the second acrylate layer.

The resulting stack exhibited an average spectral transmissionTvis=91.1% (determined by averaging the percent transmission between 400nm and 1400 nm) measured at a 0° angle of incidence. A water vaportransmission rate was measured in accordance with ASTM F-1249 at 50° C.and 100% Relative Humidity (RH) using a Water Vapor Transmission Rate(WVTR) tester obtained from MOCON, Inc., Minneapolis, Minn., under thetrade designation “MOCON PERMATRAN-W” Model 700. The result was 0.007g/m²/day. The laminate was then placed in an environmental chamber at85° C. and 85% RH for a period of 1000 hours. The average transmissionafter aging was determined to be 91.0% and the WVRT was determined to be0.018 g/m²/day. The results are summarized in Table 1.

Preparative Example 2 PET(0.13 mm)/Barrier Layer

A UV-stabilized polyethylene terephthalate (UV-PET described above)support film was first treated in a single pass with a nitrogen plasmaon the adhesion-primed surface of the incoming web. The UV-PET film wasthen re-oriented in the deposition chamber to deposit in subsequentpasses onto the non-primed surface of the incoming web. The non-primedsurface of UV-PET was treated with a nitrogen plasma and then coveredrespectively with barrier layers of acrylate, SiAlOx, SiOx, a secondacrylate, and a second SiAlOx layer. The individual plasmas and layerswere formed as follows:

(Plasma 1—plasma treatment on primed surface of UV-PET) A 450 m longroll of 0.127 mm thick×356 mm wide UV-PET film was loaded into aroll-to-roll vacuum processing chamber with the adhesion-primed (forsolvent-based materials) surface facing “up” and the non-primed side incontact with the coating drum. The chamber was pumped down to a pressureof 2×10⁻⁵ Torr. The web speed was maintained at 3.7 meters/minute whilemaintaining the backside of the film in contact with a coating drumchilled to −10° C. With the backside of the UV-PET film in contact withthe drum, a 350 m length of the frontside (adhesion-primed) film surfacewas treated with a nitrogen plasma formed by flowing 100 sccm nitrogenover a magnetically enhanced cathode in the presence of 0.02 kW of powerin a similar manner to Layer 1 in Preparative Example 1.

(Layer 1—smoothing polymeric layer) The vacuum processing chamber wasthen vented to atmosphere and the 350 m length of plasma-treated UV-PETfilm was reoriented such that the non-primed side of the UV-PET wasfacing “up” and the adhesion-primed with plasma-treatment side of theUV-PET was in contact with the coating drum. The chamber was againpumped down to a pressure of 2×10⁻⁵ Torr. The web speed was maintainedat 3.7 meters/minute while maintaining the backside of the film incontact with a coating drum chilled to −10° C. With the backside of theUV-PET film in contact with the drum, a 350 m length of the non-primedfilm surface was treated with a nitrogen plasma and coated withtricyclodecane dimethanol di-acrylate in a similar manner to Layer 1 inPreparative Example 1.

(Layer 2—inorganic layer) Immediately after the acrylate deposition andwith the film still in contact with the drum, a SiAlOx layer wassputter-deposited atop a 100 meter length of the plasma treated andacrylate-coated UV-PET film surface in a manner similar to Layer 2 inthe previous example but with the following exceptions; the total gasmixture contained 950 sccm argon and 65 sccm oxygen at a sputterpressure of 3.5 millitorr (0.47 Pa). This provided a 30 nm thick SiAlOxlayer deposited atop the acrylate coating.

(Layer 3—inorganic layer) Immediately after the SiAlOx deposition andwith the film still in contact with the drum, a sub-oxide of silicon(SiOx, where x<2) tie-layer was sputter deposited atop the same 100meter length of the SiAlOx and acrylate coated UV-PET film surface in amanner similar to Layer 3 in Preparative Example 1.

(Layer 4—protective polymeric layer) Immediately after the SiOx layerdeposition and with the film still in contact with the drum, a secondacrylate was coated and cross linked on the same 100 meter web length ina manner similar to Layer 4 in Preparative Example 1.

(Layer 5—inorganic layer) In a separate pass through the roll-to-rollvacuum processing chamber and with the web at 3.7 meters/minute, asecond SiAlOx was sputter deposited atop the same 100 meter web lengthusing the same conditions as above. This provided a 30 nm thick SiAlOxlayer deposited atop the second acrylate layer.

The resulting stack exhibited an average spectral transmissionTvis=90.0% (determined by averaging the percent transmission T between400 nm and 1400 nm) measured at a 0° angle of incidence. A water vaportransmission rate was measured in accordance with ASTM F-1249 at 50° C.and 100% RH using a WVTR tester obtained from MOCON, Inc., Minneapolis,Minn., under the trade designation “MOCON PERMATRAN-W” Model 700. Theresult was below the 0.005 g/m²/day detection limit of the system. Thelaminate was then placed in an environmental chamber at 85° C. and 85%RH for a period of 1000 hours. The average transmission after aging wasdetermined to be 89.6% and the WVRT was determined to be 0.013 g/m²/day.The results are summarized in Table 1.

Preparative Example 3 PET(0.13 mm)/Barrier Layer with Silane

A UV-stabilized polyethylene terephthalate (UV-PET described above)support film was first treated in a single pass with a nitrogen plasmaon the adhesion-primed surface, or back-side, of the incoming web. TheUV-PET film was then re-oriented in the deposition chamber to deposit insubsequent passes onto the non-primed surface, or front-side, of theincoming web. The front-side surface of UV-PET was treated with anitrogen plasma and then covered respectively with barrier layers ofacrylate, SiAlOx, a second acrylate containing a silane coupling agent,and a second SiAlOx layer. The individual plasmas and layers were formedas follows:

(Plasma 1—plasma treatment on primed surface of UV-PET) A 450 m longroll of 0.127 mm thick×356 mm wide UV-PET film was loaded into aroll-to-roll vacuum processing chamber and nitrogen plasma treated asdescribed in the Plasma 1 description of Preparative Example 2.

(Layer 1—smoothing polymeric layer) The vacuum processing chamber wasthen vented to atmosphere and the 350 m length of plasma-treated UV-PETfilm was reoriented such that the non-primed side of the UV-PET wasfacing “up” and the adhesion-primed with plasma-treatment side of theUV-PET was in contact with the coating drum. The chamber was againpumped down to a pressure of 2×10⁻⁵ Torr. The web speed was maintainedat 3.7 meters/minute while maintaining the backside of the film incontact with a coating drum chilled to −10° C. With the backside of theUV-PET film in contact with the drum, a 350 m length of the non-primedfilm surface was treated with a nitrogen plasma and coated withtricyclodecane dimethanol di-acrylate in a similar manner to Layer 1 inPreparative Example 1.

(Layer 2—inorganic layer) Immediately after the acrylate deposition andwith the film still in contact with the drum, a SiAlOx layer wassputter-deposited atop a 100 meter length of the plasma treated andacrylate-coated UV-PET film surface in a manner similar to Layer 2 inPreparative Example 1.

(Layer 3—protective polymeric layer) Immediately after the SiAlOx layerdeposition and with the film still in contact with the drum, a secondacrylate was coated and cross linked on the same 100 meter web length ina manner similar to Layer 4 in Preparative Example 1 but with thefollowing exceptions; a coupling agent,N-n-BUTYL-AZA-2,2-DIMETHOXYSILACYCLOPENTANE (commercially available as“CYCLIC AZA SILANE 1932.4” from Gelest, Morrisville, Pa.), was added tothe degassed SR-833S at 3% by mass prior to being pumped through theatomizer. The resulting monomer mixture formed a vapor stream thatcondensed onto the film surface and was polymerized after electron beamexposure using a multi-filament electron gun operated at 9.0 kV and 0.45mA to form a 725 nm acrylate layer.

(Layer 4—inorganic layer) In a separate pass through the roll-to-rollvacuum processing chamber and with the web at 3.7 meters/minute, asecond SiAlOx was sputter deposited atop the same 100 meter web lengthusing the same conditions as Layer 5 in Preparative Example 1. Thisprovided a 30 nm thick SiAlOx layer deposited atop the second acrylatelayer.

The resulting stack exhibited an average spectral transmissionTvis=90.1% (determined by averaging the percent transmission T between400 nm and 1400 nm) measured at a 0° angle of incidence. A water vaportransmission rate was measured in accordance with ASTM F-1249 at 50° C.and 100% RH using a WVTR tester obtained from MOCON, Inc., Minneapolis,Minn., under the trade designation “MOCON PERMATRAN-W” Model 700. Theresult was below the 0.005 g/m²/day detection limit of the system. Thelaminate was then placed in an environmental chamber at 85° C. and 85%RH for a period of 1000 hours. The average transmission after aging wasdetermined to be 89.7% and the WVRT was determined to be 0.186 g/m²/day.The results are summarized in Table 1.

Example 1 ETFE(0.13 mm)/“8172P”/Barrier Layer/PET(0.13 mm)

Examples of laminated barrier assemblies were made on a roll-to-roll,rubber to steel roller laminator, similar to the GBC Pro-Tech Orca II(available from GBC Pro-Tech, De Forest, Wis.). The laminatedconstruction was formed as follows.

The barrier film from Preparative Example 2 was loaded into aroll-to-roll laminator with the coated stack facing “up” and thenon-coated stack side facing the idler faces. A 300 meter roll oftwo-sided release liner 50 micron acrylic pressure sensitive adhesive(“3M OPTICALLY CLEAR ADHESIVE 8172P”) was loaded into the same laminatorwith the “up” side liner peeled off and rewound onto an auxiliaryrewinder. The two films were brought into contact through a rubber tosteel nip roller system. Tension of each of the films was controlledusing a spring brake such that the resulting laminate was flat. The aircylinder actuator controlling the lamination pressure was set at 2.6×10⁵Pa (38 psi). The web speed was maintained at 4.6 m/min (15 feet/min)throughout lamination of the two films. The rubber roller and steelrollers were both kept at room temperature. The resulting laminatedconstruction consisting of film from Preparative Example 2, adhesive,and release liner was rewound with the acrylic pressure sensitiveadhesive on the “outside” of the wound roll.

The output laminated construction roll was removed and loaded into thelaminator with the release liner facing “up” and the non-coated side offilm from Preparative Example 2 facing the idlers. The remaining releaseliner was peeled off to expose the adhesive and rewound onto anauxiliary rewinder. A 300 meter long roll of 125 micron, two sideC-treated ETFE was loaded into the same laminator. The two films werebrought into contact through a rubber to steel nip roller system.Tension of each of the films was controlled using a spring brake suchthat the resulting laminate was flat. The air cylinder actuatorcontrolling the lamination pressure was set at 2.6×10⁵ Pa (38 psi). Theweb speed was maintained at 4.6 m/min (15 feet/min) throughoutlamination of the two films. The rubber roller and steel rollers wereboth kept at room temperature. The resulting laminated constructionconsisted of Preparative Example 2, 8172P adhesive, and two-sideC-treated ETFE.

The resulting stack exhibited an average spectral transmissionTvis=90.0% (determined by averaging the percent transmission T between400 nm and 1400 nm) measured at a 0° angle of incidence. A water vaportransmission rate was measured in accordance with ASTM F-1249 at 50° C.and 100% RH using a WVTR tester obtained from MOCON, Inc., Minneapolis,Minn., under the trade designation “MOCON PERMATRAN-W” Model 700. Theresult was below the 0.005 g/m²/day detection limit of the system. Thelaminate was then placed in an environmental chamber at 85° C. and 85%RH for a period of 1000 hours. The average transmission after aging wasdetermined to be 89.6% and the WVRT was determined to be 0.007 g/m²/day.The results are summarized in Table 1.

Example 2 ETFE(0.13 mm)/“8172P”/Barrier Layer with Silane/PET(0.13 mm)

A laminated barrier assembly was made as in Example 1 except that thebarrier film of Preparative Example 3 was used in place of the barrierfilm of Preparative Example 2. The resulting laminated constructionconsisted of Preparative Example 3, 8172P adhesive, and two-sideC-treated ETFE.

The resulting stack exhibited an average spectral transmissionTvis=90.0% (determined by averaging the percent transmission T between400 nm and 1400 nm) measured at a 0° angle of incidence. A water vaportransmission rate was measured in accordance with ASTM F-1249 at 50° C.and 100% RH using a WVTR tester obtained from MOCON, Inc., Minneapolis,Minn., under the trade designation “MOCON PERMATRAN-W” Model 700. Theresult was below the 0.005 g/m²/day detection limit of the system. Thelaminate was then placed in an environmental chamber at 85° C. and 85%RH for a period of 1000 hours. The average transmission after aging wasdetermined to be 89.6% and the WVRT was below the 0.005 g/m²/daydetection limit of the system. The results are summarized in Table 1.

TABLE 1 1000 hr 1000 hr Initial 85/85 85/85 WVTR WVTR % T % T (g/m²/day)(g/m²/day) Preparative Example 1 91.1 91.0 0.007 0.018 PreparativeExample 2 90.0 89.6 BDL 0.013 Preparative Example 3 90.1 89.7 BDL 0.186Example 1 90.0 89.6 BDL 0.007 Example 2 90.0 89.6 BDL BDL BDL = BelowDetectable Limit

Comparative Example 1 Stainless-Steel (25 Micron)/Encapsulant “ADCO PVA”(0.46 mm)/ETFE(0.13 mm) Laminate

A 1.3 cm (0.5 inch)×10 cm (4 inch) laminate comprising the followingthree layers was stacked in the following order:

(Layer 1) A 1.3 cm (0.5 inch)×10 cm (4 inch), 25 micron (0.001 inch)thick strip of Stainless-Steel (commercially available under the tradename “Starrett 666-1” feeler gage) was placed on top of a 30.5 cm (12inch)×46 cm (18 inch)×0.51 cm (0.2 inch) glass panel.

(Layer 2) A 1.3 cm (0.5 inch)×10 cm (4 inch), 0.46 mm (0.018 inch) thicklayer of encapsulant “ADCO PVA” was placed directly on top of Layer 1.

(Layer 3) A 1.3 cm (0.5 inch)×10 cm (4 inch), 0.13 mm (0.005 inch) thickEthylene-TetraFluoroEthylene (ETFE) was placed directly on top of layer2.

A 30.5 cm (12 inch)×46 cm (18 inch)×0.51 cm (0.2 inch) glass panel wasthen placed on top of the above described three layer stack. The glasspanel weighed 1.5 kg (3.4 lbs). The three stack layer between glasspanels was then put in a 150° C. oven for 10 minutes. In the oven, theencapsulant “ADCO PVA” melted and upon cooling solidified and bonded theETFE layer and the Stainless Steel layer. After the 10 minutes durationthe specimen was taken out of the oven and cooled down to roomtemperature. Then the excess encapsulant “ADCO PVA” that flowed past theedges of the ETFE and Stainless-Steel layers was trimmed with a pair ofscissors. Then the curl of the trimmed sample was measured as describedin “Curl Test Method” as an indication of the amount of residual stressremaining after the high temperature lamination process. For theComparative Example 1 laminate, the specimen was noted to have acurvature of 9 m⁻¹. Curl results are shown in Table 2.

Example 3 PET with Barfier (0.13 mm)/PSA(51 micron)/ETFE(0.13 mm)Laminate

A 1.3 cm (0.5 inch)×10 cm (4 inch), 0.13 mm (0.005 inch) thickUV-stabilized PolyEthylene Terephthalate (UV-PET) with barrier layer asdescribed in Preparative Example 3 was hand laminated to a 1.3 cm (0.5inch)×10 cm (4 inch), 0.13 mm (0.005 inch) thickEthylene-TetraFluoroEthylene (ETFE) layer using a 51 micron (0.002 inch)thick PSA-A layer. This lamination was done by first laying the PETlayer on a table with the barrier coated side facing up. Then one linerfrom one side of the PSA was removed and the PSA placed on top of thePET layer with freshly exposed PSA side in contact with the barriercoated PET side. The second liner remaining on the PSA was then peeledfrom the PSA and a sheet of 0.13 mm (0.005 inch) thick ETFE film waslaid onto the second side of the PSA. A rubber hand roller was rolledback and forth on the PET/PSA/ETFE laminate to promote adhesion of thestack.

In order to test the PET/PSA/ETFE laminate, a 1.3 cm (0.5 inch)×10 cm (4inch) strip of the laminate was prepared by using 1.3 cm (0.5 inch) wideparallel blade cutting knife. A 1.3 cm (0.5 inch)×10 cm (4 inch), 25micron (0.001 inch) thick strip of stainless-steel feeler gage wasplaced on a 30.5 cm (12 inch)×46 cm (18 inch)×0.51 cm (0.2 inch) glasspanel. A 1.3 cm (0.5 inch)×10 cm (4 inch), 0.46 mm (0.018 inch) thicklayer of encapsulant “ADCO PVA” was placed directly on top of thestainless steel strip. The 1.3 cm (0.5 inch)×10 cm (4 inch) laminate wasthen placed on top of the encapsulant “ADCO PVA” layer with the PET sideof the laminate in contact with the encapsulant “ADCO PVA” layer.Finally a 30.5 cm (12 inch)×46 cm (18 inch)×0.51 cm (0.2 inch) glasspanel was placed on top of the above described five layer laminate. Thetop glass panel weighed 1.5 kg (3.4 lbs). The five layer laminatebetween glass panels was then placed into 150° C. oven for 10 minutes.In the oven, the encapsulant “ADCO PVA” melted and upon coolingsolidified bonding of the top three layer laminate and the StainlessSteel layer. After the 10 minutes duration the specimen was taken fromthe oven and cooled down to room temperature. The excess encapsulant“ADCO PVA” that had flowed past the edges of the top three layerlaminate and stainless-steel layers was trimmed with a pair of scissors.The curl of the trimmed sample was measured as described in “Curl TestMethod” as an indication of the amount of residual stress caused by thehigh temperature lamination process. The specimen was noted to have acurvature of 3 m⁻¹. Curl results are shown in Table 2.

Example 4 PET with Barrier (0.13 mm)/PSA(51 Micron)/ETFE(51 micron)Laminate

A laminate was prepared as in Example 3, but with a 51 micron thick ETFElayer. Strips of the laminate attached to a stainless-steel backing wereprepared as in Example 3 and the curl was measured as described in “CurlTest Method” as an indication of the amount of residual stress caused bythe high temperature lamination process. The specimen was noted to havea curvature of 2.5 m⁻¹. Curl results are shown in Table 2.

Example 5 PET with Barrier (51 Micron)/PSA(51 Micron)/ETFE(0.13 Mm)Laminate

A laminate was prepared as in Example 3, but with a 51 micron PETbarrier layer as described in Preparative Example 3. Strips of thelaminate attached to a stainless-steel backing were prepared as inExample 1 and the curl was measured as described in “Curl Test Method”as an indication of the amount of residual stress caused by the hightemperature lamination process. The specimen was noted to have acurvature of 6.5 m⁻¹. Curl results are shown in Table 2.

TABLE 2 Stain- less ADCO steel PVA PET PSA Bar- ETFE Curl (micron)(micron) (micron) (micron) rier (micron) (m⁻¹) Compar- 25 460 NONE NONENO 130 9.0 ative Ex- ample 1 Example 25 460 130 51 YES 130 3.0 3 Example25 460 130 51 YES  51 2.5 4 Example 25 460  51 51 YES 130 6.5 5

Example 6 ETFE(51 Micron)/“8172P”/Barrier Layer with Silane/PET(0.13 mm)

A laminated barrier assembly made as in Example 2 except that the ETFElayer was 51 microns thick. The resulting stack exhibited an averagespectral transmission Tvis=90.8% (determined by averaging the percenttransmission T between 400 nm and 1400 nm) measured at a 0° angle ofincidence. Transmission data is shown in Table 3.

Example 7 “SCOTCHCAL 3640 GPS”/Barrier Layer with Silane/PET(0.13 mm)

A 152 mm×152 mm laminate was assembled at room temperature ambientconditions as follows: A 152 mm×152 mm piece of film “SCOTCHCAL 3640GPS” was laminated using hand pressure and a felt squeegee by firstremoving the protective paper release liner and then placing theadhesive in contact to the barrier side of Preparative Example 3. Handpressure and a felt squeegee were used to laminate the layers. Theresulting stack exhibited an average spectral transmission Tvis=89.1%(determined by averaging the percent transmission T between 400 nm and1400 nm) measured at a 0° angle of incidence. Transmission data is shownin Table 3.

Example 8 PVDF (0.05 mm)/“8172P”/Barrier Layer with Silane/PET(0.13 mm)

A 152 mm×152 mm laminate was assembled at room temperature ambientconditions as follows: A 152 mm×152 mm piece of “8172P” adhesivecontaining two protective release liners was laminated using handpressure and a felt squeegee by first removing one of the clearprotective release liner and then placing the adhesive in contact to thebarrier side of Preparative Example 3. Hand pressure and a felt squeegeewere used to laminate the layers. The second clear protective releaseliner was then removed from the “8172P” adhesive such that now the PVDFfilm was placed in contact with the “8172P” adhesive and laminated tothe assembly using hand pressure and felt squeegee. The resulting stackexhibited an average spectral transmission Tvis=91.6% (determined byaveraging the percent transmission T between 400 nm and 1400 nm)measured at a 0° angle of incidence. Transmission data is shown in Table3.

Example 9 PVDF (0.05 mm)/PSA-A/Barrier Layer with Silane/PET(0.13 mm)

A laminated barrier assembly was made as in Example 8 except that the“8172P” adhesive was replaced with PSA-A adhesive. The resulting stackexhibited an average spectral transmission Tvis=91.0% (determined byaveraging the percent transmission T between 400 nm and 1400 nm)measured at a 0° angle of incidence. Transmission data is shown in Table3.

TABLE 3 Example % T 6 90.8 7 89.1 8 91.6 9 91.0

Example 10 T-Peel Tests for Various Laminates

Various laminate samples were constructed for T-Peel testing. Sample Awas made as follows: A 178 mm wide×178 mm long laminate (having a 25 mmunbonded end for clamping in the grips of the test machine) for T-Peeltesting was made comprising the following layers that were stacked inthe following order:

(Layer 1) A 178 mm×178 mm solar backsheet film (Madico TAPE) wasorientated with the 100 micron ethylene vinylacetate (EVA) layer facingup.

(Layer 2) A 178 mm wide×152 mm long sample of Etimex 496.10 was placedon top of Layer 1 after removing the release liner.

(Layer 3) A 178 mm×178 mm sample of Preparative Example 1 Barrier Filmwith the barrier surface facing the Etimex 496.10 layer was placed suchthat it is directly aligned on top of Layer 1 and completely coveringLayer 2. These layers were then placed into a Spire 350 Vacuum Laminator(commercially available from Spire Corporation Bedford, Mass.). Thelaminate was then cured for 12 minutes at 150° C. under 1 atm (1×10⁵ Pa)of pressure. The resulting laminate was then cut into 25 mm wide×152 mmlong strips such that one end contains the 25 mm unbonded films that areto be placed in the clamping grips of the test machine. The two unbondedends of film were placed in a tension testing machine and T-Peel testingwas then completed as described in “T-Peel Test Method.” The averagepeak peel force was determined to be 3.2 N/cm (1.8 lbf/in).

Sample B was constructed as described for Sample A except that thebarrier layer of Preparative Example 2 was used in place of the barrierlayer of Preparative Example 1. T-Peel testing was then completed asdescribed in “T-Peel Test Method.” The average peak peel force wasdetermined to be 5.3 N/cm (3.0 lbf/in).

Sample C was constructed as described for Sample A except that thebarrier layer of Preparative Example 3 was used in place of the barrierlayer of Preparative Example 1. T-Peel testing was then completed asdescribed in “T-Peel Test Method.” The average peak peel force wasdetermined to be 21.2 N/cm (12.1 lbf/in). The results are summarized inTable 4.

Sample D was constructed as described for Sample A except that thebarrier layer of Example 1 was used in place of the barrier layer ofPreparative Example 1. T-Peel testing was then completed as described in“T-Peel Test Method.” The average peak peel force was determined to be75.3 N/cm (43.0 lbf/in).

Sample E was constructed as described for Sample A except that thebarrier layer of Example 2 was used in place of the barrier layer ofPreparative Example 1. T-Peel testing was then completed as described in“T-Peel Test Method.” The average peak peel force was determined to be66.4 N/cm (37.9 lbf/in).

The results of the peel tests are summarized in Table 4.

TABLE 4 Sample Peel Force (N/cm) A 3.2 B 5.3 C 21.1 D 75.3 E 66.4

Example 11 T-Peel and Curl Tests for Various Laminates

Various laminate samples were constructed for T-Peel testing and curltesting. Sample G was constructed as Sample A of Example 10 except that“JURASOL® TL”, was used in place of Etimex 496.10. Samples H-L wereprepared by similarly laminating the barrier film of Examples 1, 2, 7,8, and 9, respectively, to Madico TAPE using “JURASOL® TL”.

T-Peel testing was completed as described in “T-Peel Test Method” andCurl measurements were completed on 13 mm wide×100 mm long strips asdescribed in “Curl Test Method.” The results are summarized in Table 5.

TABLE 5 Sample Peel Force (N/cm) Curl (m⁻¹) G 0.4 7.9 H 17.7 1.6 I 18.61.6 J 29.9 1.6 K 16.3 1.6 L 36.8 1.6

Example 12 Barrier, Curl and Delamination Properties

Sample M was made as follows: A layer of encapsulant “ADCO PVA” wasapplied to a 15 cm×15 cm (6 inch×6 inch) glass substrate. A first 0.035mm thick strip of tinned copper foil 128 mm long by about 12 mm wide wasplaced on top of the encapsulant “ADCO PVA” with the length direction ofthe strip along the diagonal of the glass substrate. A second stainlesssteel strip, which had similar dimensions to the first strip was appliedto the encapsulant “ADCO PVA” layer above the first strip and orientedalong the opposite diagonal direction. A second encapsulant “ADCO PVA”layer was then applied over the stainless steel strips and a 0.13 mmthick PET layer was applied over the second encapsulant layer. Thelaminate was then cured for 12 minutes at 150° C. under 1 atm (1×10⁵ Pa)of pressure. The sample was then subjected to 12 humidity freeze cyclesaccording to IEC 61215 Humidity freeze Test (10.12) and no delaminationswere observed. The curl was measured according to “Curl Test Method” andfound to be 0.4 m⁻¹.

A second laminate was made by applying a layer of encapsulant “ADCO PVA”to a 15 cm×15 cm (6 inch×6 inch) glass substrate and then applying a 114mm×114 mm humidity indicator card (obtained from Sud-Chemie PerformancePackaging Colton, Calif., under the trade designation “HUMITECTORMaximum Humidity Indicator P/N MXC-56789”) on top of the encapsulant“ADCO PVA”. A second encapsulant “ADCO PVA” layer was placed over thehumidity indicator card and a 0.13 mm thick PET layer was applied overthe second encapsulant layer. The laminate was then cured for 12 minutesat 150° C. under 1 atm (1×10⁵ Pa) of pressure. The resulting laminatewas placed in an environmental chamber at 85° C. and 85% RH for a periodof 100 hours. Upon 100 hours of 85° C. and 85% RH exposure the humidityindicator card was visually examined and the 80% indicator had dissolvedcrystals. This indicates that the humidity indicator sensor was exposedto at least 80% RH for 24 hours.

Sample N was made as follows: Laminates with tinned copper foil stripsand with a humidity sensor strip were constructed as described forSample M except that the PET layer was replaced with a 0.13 mm thickETFE layer. The laminate with the tinned copper foil strips wassubjected to 12 humidity freeze cycles and no delamination was observed.The curl was measured according to “Curl Test Method” and found to be0.4 m⁻¹. A humidity test was done as described for Sample M and thisindicated that the humidity indicator sensor was exposed to at least 80%RH for 24 hours.

Sample O was made as follows: Laminates with tinned copper foil stripsand with a humidity sensor strip were constructed as described forSample M except that the PET layer was replaced with the barrier film ofPreparative Example 1 with the barrier side of the barrier film facingthe encapsulant “ADCO PVA” layers. The laminate with the tinned copperfoil strips was subjected to 12 humidity freeze cycles and delaminationswere observed around all edges. The curl was measured according to “CurlTest Method” and found to be 0.4 m⁻¹. A humidity test was done asdescribed for Sample M and this indicated that the humidity indicatorsensor was exposed to at least 50% RH for 24 hours.

Sample P was made as follows: Laminates with tinned copper foil stripsand with a humidity sensor strip were constructed as described forSample M except that the PET layer was replaced with the barrier film ofExample 6 with the barrier side of the barrier film facing theencapsulant “ADCO PVA” layers. The laminate with the tinned copper foilstrips was subjected to 12 humidity freeze cycles and no delaminationwas observed. The curl was measured according to “Curl Test Method” andfound to be 0.4 m⁻¹. A humidity test was done as described for Sample Mand this indicated that the humidity indicator sensor was exposed to atleast 50% RH for 24 hours.

Sample Q was made as follows: Laminates with tinned copper foil stripsand with a humidity sensor strip were constructed as described forSample M except that the glass layer was replaced with a 15 cm×15 cm×25micron (6 inch×6 inch×0.001 inch) stainless steel feeler gage material.The laminate with the tinned copper foil strips was subjected to 12humidity freeze cycles and no delamination was observed. The curl wasmeasured according to “Curl Test Method” and found to be 0.4 m¹. Ahumidity test was done as described for Sample M and this indicated thatthe humidity indicator sensor was exposed to at least 80% RH for 24hours.

Sample R was made as follows: Laminates with tinned copper foil stripsand with a humidity sensor strip were constructed as described forSample Q except that the PET layer was replaced with a 0.13 mm ETFElayer. The laminate with the tinned copper foil strips was subjected to12 humidity freeze cycles and no delamination was observed. The curl wasmeasured according to “Curl Test Method” and found to be 2.0 m⁻¹. Ahumidity test was done as described for Sample M and this indicated thatthe humidity indicator sensor was exposed to at least 80% RH for 24hours.

Sample S was made as follows: Laminates with tinned copper foil stripsand with a humidity sensor strip were constructed as described forSample Q except that the PET layer was replaced with the barrier film ofPreparative Example 1 with the barrier side of the barrier film facingthe encapsulant “ADCO PVA” layers. The laminate with the tinned copperfoil strips was subjected to 12 humidity freeze cycles and delaminationwas observed around the tinned copper foil strips. The curl was measuredaccording to “Curl Test Method” and found to be 2.0 m⁻¹. A humidity testwas done as described for Sample M and this indicated that the humidityindicator sensor was exposed to at least 50% RH for 24 hours.

Sample T was made as follows: Laminates with tinned copper foil stripsand with a humidity sensor strip were constructed as described forSample Q except that the PET layer was replaced with the barrier film ofExample 6 with the barrier side of the barrier film facing theencapsulant “ADCO PVA” layers. The laminate with the tinned copper foilstrips was subjected to 12 humidity freeze cycles and no delaminationwas observed. The curl was measured according to “Curl Test Method” andfound to be 0.4 m⁻¹. A humidity test was done as described for Sample Mand this indicated that the humidity indicator sensor was exposed to atleast 50% RH for 24 hours.

The data for Samples M-T is summarized in Table 6.

TABLE 6 12 Humidity Freeze Cycles 100 Hr 85/85 (delamination SampleHumidity Indicator Curl (m⁻¹) Yes/No) M 80% 0.4 No N 80% 0.4 No O 50%0.4 Yes P 50% 0.4 No Q 80% 0.4 No R 80% 2.0 No S 50% 2.0 Yes T 50% 0.4No

Prophetic Example

Instead of the ETFE film described above, a UV reflective multilayeroptical film can be used as the substrate. Nitrogen plasma surfacetreatment can be used as described above. The adhesion and barrierproperties described above would be expected to be similar when a UVreflective multilayer optical film is used. A multilayer optical filmcan be made with first optical layers of polyethylene terephthalate(PET) (obtained from Eastman Chemical, Kingsport, Tenn., under the tradedesignation “EASTAPAK 7452”) and second optical layers of a copolymer of75 weight percent methyl methacrylate and 25 weight percent ethylacrylate (coPMMA) (obtained from Ineos Acrylics, Inc., Memphis, Tenn.,under the trade designation “PERSPEX CP63”). The PET and coPMMA can becoextruded through a multilayer polymer melt manifold to form a stack of224 optical layers. The layer thickness profile (layer thickness values)of this UV reflector can be adjusted to be approximately a linearprofile with the first (thinnest) optical layers adjusted to have abouta ¼ wave optical thickness (index times physical thickness) for 300 nmlight and progressing to the thickest layers which can be adjusted to beabout ¼ wave thick optical thickness for 400 nm light. Layer thicknessprofiles of such films can be adjusted to provide for improved spectralcharacteristics using the axial rod apparatus disclosed in U.S. Pat. No.6,783,349 (Neavin et al.), the disclosure of which is incorporatedherein by reference, combined with layer profile information obtainablewith atomic force microscopic techniques. 20 wt % of UV absorbermasterbatch (e.g., “Sukano TA07-07MB”) can be extrusion compounded intoboth the first optical layers (PET) and second optical layers (coPMMA).

In addition to these optical layers, non-optical protective skin layersof PET (260 micrometers thickness each) can be coextruded on either sideof the optical stack. 20 wt % of UV absorber masterbatch (e.g., “SukanoTA07-07MB”) can be compounded into these PET protective skin layers.This multilayer coextruded melt stream can be cast onto a chilled rollat 5.4 meters per minute creating a multilayer cast web approximately500 micrometers (20 mils) thick. The multilayer cast web can then bepreheated for about 10 seconds at 95° C. and biaxially oriented at adraw ratios of 3.5×3.7. The oriented multilayer film can be furtherheated at 225° C. for 10 seconds to increase crystallinity of the PETlayers.

All patents and publications referred to herein are hereby incorporatedby reference in their entirety. Various modifications and alterations ofthis disclosure may be made by those skilled in the art withoutdeparting from the scope and spirit of this disclosure, and it should beunderstood that this disclosure is not to be unduly limited to theillustrative embodiments set forth herein.

What is claimed is:
 1. A barrier film comprising: a polymeric filmsubstrate; and at least first and second polymer layers separated by aninorganic barrier layer, wherein the first polymer layer is disposed onthe polymeric film substrate, and wherein at least one of the first orsecond polymer layers is prepared from co-deposited amino silane andacrylate or methacrylate monomer.
 2. The barrier film of claim 1,wherein the amino silane is represented by formulaZ₂N-L-SiY_(x)Y′_(3-x), wherein each Z is independently hydrogen or alkylhaving up to 12 carbon atoms, L is alkylene having up to 12 carbonatoms, x is 1, 2, or 3, Y is a hydrolysable group, and Y′ is anon-hydrolysable group.
 3. The barrier film of claim 2, wherein Y isalkoxy having up to 12 carbon atoms or halogen, and wherein Y′ is alkylhaving up to 12 carbon atoms.
 4. The barrier film of claim 2, whereinthe amino silane is capable of forming a siloxane bond with a metaloxide surface.
 5. The barrier film of claim 2, wherein the amino silaneis selected from the group consisting of 3-aminopropyltrimethoxysilane;3-aminopropyltriethoxysilane; 4-aminobutyltrimethoxysilane;4-aminobutyltriethoxysilane;3-aminopropyltris(methoxyethoxyethoxy)silane;3-aminopropylmethyldiethoxysilane;3-(N-methylamino)propyltrimethoxysilane;3-aminopropylmethyldimethoxysilane; 3-aminopropyldimethylmethoxysilane;and 3-aminopropyldimethylethoxysilane.
 6. The barrier film of claim 2,wherein one Z is hydrogen and the other Z is alkyl having up to 12carbon atoms.
 7. The barrier film of claim 1, wherein the first orsecond polymer layer is prepared from components consisting of theco-deposited amino silane and acrylate or methacrylate monomer.
 8. Thebarrier film of claim 1, wherein the amino silane is a secondary aminosilane.
 9. The barrier film of claim 1, wherein the amino silane isselected from the group consisting of aminopropyltrimethoxysilane;3-aminopropyltriethoxysilane;3-(2-aminoethyl)aminopropyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,bis-(gamma-triethoxysilylpropyl)amine;N-(2-aminoethyl)-3-aminopropyltributoxysilane;6-(aminohexylaminopropyl)trimethoxysilane; 4-aminobutyltrimethoxysilane;4-aminobutyltriethoxysilane;3-aminopropyltris(methoxyethoxyethoxy)silane;3-aminopropylmethyldiethoxysilane;3-(N-methylamino)propyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane;N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane;N-(2-aminoethyl)-3-aminopropyltrimethoxysilane;N-(2-aminoethyl)-3-aminopropyltriethoxysilane;3-aminopropylmethyldiethoxysilane; 3-aminopropylmethyldimethoxysilane;3-aminopropyldimethylmethoxysilane; and3-aminopropyldimethylethoxysilane.
 10. The barrier film of claim 1,wherein the inorganic barrier layer is an oxide layer that shares asiloxane bond with at least one of the first or second polymer layers.11. The barrier film of claim 1, wherein the barrier film comprisesseveral alternating inorganic barrier layers and first or second polymerlayers.
 12. The barrier film of claim 1, wherein the inorganic barrierlayer is a metal oxide layer.
 13. The barrier film of claim 1, whereinthe second polymer layer is prepared from co-deposited amino silane andacrylate or methacrylate monomer, and wherein the second polymer layeris the top polymer layer of the barrier film, furthest away from thepolymeric film substrate.
 14. The barrier film of claim 1, wherein theacrylate or methacrylate monomer is selected from the group consistingof hexanediol diacrylate, 1,6-hexanediol dimethacrylate, ethoxyethylacrylate, ethoxyethyl methacrylate, cyanoethyl acrylate, cyanoethylmethacrylate, isobornyl acrylate, isobornyl methacrylate, octadecylacrylate, octadecyl methacrylate, isodecyl acrylate, isodecylmethacrylate, lauryl acrylate, lauryl methacrylate, beta-carboxyethylacrylate, beta-carboxyethyl methacrylate, tetrahydrofurfuryl acrylate,tetrahydrofurfuryl methacrylate, pentafluorophenyl acrylate,pentafluorophenyl methacrylate, nitrophenyl acrylate, nitrophenylmethacrylate, 2-phenoxyethyl acrylate, 2-phenoxyethyl methacrylate,2,2,2-trifluoromethyl (meth)acrylate, diethylene glycol diacrylate,diethylene glycol dimethacrylate, triethylene glycol diacrylate,triethylene glycol dimethacrylate, tripropylene glycol diacrylate,tripropylene glycol dimethacrylate, tetraethylene glycol diacrylate,tetraethylene glycol dimethacrylate, neopentyl glycol diacrylate,neopentyl glycol dimethacrylate, propoxylated neopentyl glycoldiacrylate, propoxylated neopentyl glycol dimethacrylate, polyethyleneglycol diacrylate, polyethylene glycol dimethacrylate, bisphenol A epoxydiacrylate, bisphenol A epoxy dimethacrylate, ethoxylated (4) bisphenolA dimethacrylate, ethoxylated (4) bisphenol A diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylol propane triacrylate,propylated trimethylol propane triacrylate, trimethylol propanetrimethacrylate, ethoxylated trimethylol propane trimethacrylate,propylated trimethylol propane trimethacrylate,tris(2-hydroxyethyl)isocyanurate triacrylate,tris(2-hydroxyethyl)isocyanurate trimethacrylate, pentaerythritoltriacrylate, pentaerythritol trimethacrylate, dipentaerythirtolpentaacrylate, dipentaerythirtol pentamethacrylate, phenylthioethylacrylate, phenylthioethyl methacrylate, naphthloxyethyl acrylate,naphthloxyethyl methacrylate, tricyclodecane dimethanol diacrylate,tricyclodecane dimethanol dimethacrylate, di-trimethylolpropanetetraacrylates, di-trimethylolpropane tetramethacrylates, 1,3-butyleneglycol diacrylate, 1,3-butylene glycol dimethacrylate, pentaerythritoltetraacrylate, pentaerythritol tetramethacrylate, cyclohexane dimethanoldiacrylate, cyclohexane dimethanol dimethacrylate, and mixtures thereof.15. The barrier film of claim 1, wherein the acrylate or methacrylatemonomer is not a silane.
 16. A method of making the barrier film ofclaim 1, the method comprising: providing the first polymer layercrosslinked and disposed on the polymeric film substrate; applying theinorganic barrier layer to the first polymer layer; co-depositing theamino silane and the acrylate or methacrylate monomer onto the inorganicbarrier layer to provide the second polymer layer; and polymerizing theacrylate or methacrylate monomer.
 17. The method of claim 16, whereinco-depositing comprises co-evaporating the amino silane and the acrylateor methacrylate monomer.
 18. The method of claim 16, whereinco-depositing comprises evaporating a mixture of the amino silane andthe acrylate or methacrylate monomer.
 19. The method of claim 16,wherein the amino silane is represented by formulaZ₂N-L-SiY_(x)Y′_(3-x), wherein each Z is independently hydrogen or alkylhaving up to 12 carbon atoms, L is alkylene having up to 12 carbonatoms, x is 1, 2, or 3, Y is a hydrolysable group, and Y′ is anon-hydrolysable group.
 20. The method of claim 16, wherein the acrylateor methacrylate monomer is not a silane.